Aku

"Long ago in a distant land, I, Aku, the Shapeshifting Master of Darkness, unleashed an unspeakable evil. But a foolish samurai warrior wielding a magic sword stepped forth to oppose me. Before the final blow was struck, I tore open a portal in time, and flung him into the future where my evil is law. Now the fool seeks to return to the past and undo the future that is Aku."

- Aku

Aku is the main antagonist of the series Samurai Jack. Born from The Black Mass of Darkness, Aku was an evil, shape-shifting demon who took over the world and ruled it for countless eons, the arch-nemesis of Samurai Jack and the biological father of Ashi and her twin sisters. Throughout seasons 1-4, Aku was voiced by Mako, but due to his death in 2006, Aku was voiced by Greg Baldwin in Season 5.

Aku constantly antagonized Samurai Jack: he often attacked him when he was weak, and other times defended himself from Jack's own gambits. Prior to Ashi sending Jack back in time to vanquish Aku's past self, the two seem doomed never to defeat each other, and while Jack had beaten Aku on numerous occasions, Aku merely transformed into a creature, retreated, and usually called out a taunt over his shoulder. Aku was entirely aware of his inability to defeat Jack and even lamp-shaded that in "Episode XLVIII: Jack versus Aku", which eventually discouraged him from fighting Jack further. Aku could have been considered the Deuteragonist of the series as a whole (albeit a rare, villainous one), as while Ashi became that in Season 5. Aku had the most focus in the narrative besides Jack.

While he's usually presented as a serious and threatening foe, Aku was also a source of comedy in the show, due to his outrageous design and sometimes wise-guy behavior, that was supported by Mako's over the top voice-acting.

Aku means "Evil" in Japanese. It is written as "悪" in Kanji. The kanji can also be pronounced as "Waru".

In Samurai Jack: Battle Through Time, Aku made a last ditch attempt effort to save his existence and secure his rule in the future.

Personality
Aku was Evil Incarnate; he embodied the very essence of an evil overlord. Cruel and domineering to all that he met, it was obey or be obliterated with Aku. Arrogant, temperamental, callous, and sadistic by default, Aku ruled the Earth for thousands of years and did not take kindly to disobedience. Aku was responsible for countless genocides, with cities, towns, villages, and small settlements being completely destroyed, alongside all their inhabitants, while nature itself was left to rot or was decimated in order to make room for Aku's strongholds. It was likely that religions were also affected, given Aku's loathing toward all that was good and sacred.

Furthermore, lack of any divine intervention from the Gods allowed Aku to conquer Earth and rule its inhabitants with an iron fist. While Aku had recreated numerous lands into his own image, he was often just as satisfied with leaving entire areas barren wastelands and saw the carnage as reminders of his power to the general populace. Atrocities were a daily occurrence since Aku's rule, as he welcomed wanted criminals from across the galaxy, provided them with areas that were still fully occupied, and entrusted the new arrivals to wipe the inhabitants from the Earth.

When he was faced with opposition, Aku found enjoyment in slaughtering thousands of rebel armies with ease, and often made one's circumstances even worse than death if they still longed to fight him. Such was the case of the Lava Monster who fought against Aku, even as Aku decimated all of his warriors. As punishment, Aku encased the man in a crystal and forced him to watch as he slaughtered everyone that he loved, destroyed his kingdom, placed him within the depths of a mountain, and refused to grant him a warrior's death. A similar action was performed shortly after Aku's true birth: he forced Jack's father, the Emperor, to watch him begin his reign of terror on his homeland.

To increase his already formidable power, Aku also plundered the world, and countless other planets, of its resources and enslaved surrounding species to do the heavy lifting. Those that refused were often tortured and executed, as with the case of Jack's people and canine archaeologists. Numerous scientists were recruited, so that Aku may leverage their intelligence in order to create an unstoppable army of robots to take over various lands considerably quicker and eliminate more carefully hidden pockets of resistance. Aku's powers were even able to conjure up demons or monstrosities, who were then unleashed upon the land in order to create further sorrow and misery.

Aku was outright unhinged, merciless and inhumane, to say the least, but had enough of an understanding of humanity in order to manipulate the feelings of others: Aku often blackmailed others in performing his will and then betrayed his promises to them once they fulfilled their services. Aku was as intelligent as he was powerful, and his cunning knew little end, from taking the form of a woman in order to trick Jack or manipulated various races into serving him. Aku was also dishonest and had no shame or remorse, and routinely went back on his word either to serve himself or simply for amusement.

Aku took excessive pleasure in slave labor and enslaved countless races across the universe. Those slaves were often forced to build monuments in Aku's likeness and mined precious resources. When they failed to do so, the slaves were punished terribly and were sometimes executed, such in the case of the talking canines. The slaves of Aku's empire often died due to exhaustion or lack of food and were replaced with more slaves. Aku particularly enjoyed doing this to great or powerful people such as the Emperor and saw it as the ultimate insult by allowing royalty to spend the rest of their lives as helpless slaves.

Despite that, Aku possessed a dry sense of humor and often joked when he was in a good mood and mocked Jack whenever or however he could. For instance, in Episode XIV: Jack Learns to Jump Good, Aku held a time portal just out of Jack's reach just as Jack jumped for it. Aku was also rather "genre savvy", and occasionally leaned on the Fourth Wall or lamp-shaded either his own villainous tendencies or various cliche situations. Aku was also a frequent source of comic relief in the show, due, in prime, to his reactions to the things around him.

While Aku seemed to have a soft spot for children at times, that seemed to be most indicative of his views of seeing immense value in not simply eradicating them, but rather to convince them via various means to view him as the "hero" of the planet and not Samurai Jack and make them useful servants in the future in order to shape successive generations. That was seen in Episode XIII: Aku's Fairy Tales, where Aku attempted to make children admire him and told them tales that depicted himself as a hero and Jack as a villain.

Unfortunately for Aku, the children weren't impressed hearing his increasingly ludicrous tales, which then caused him to vanish in rage after he roared "the end". In Episode XXVIII: Jack and the Rave, Aku composed an evil techno music that hypnotized children, which, again, showcased his lust to indoctrinate young kids into his evil ways and made them dance for him and commit crimes. In Episode C, Aku seemingly welcomed Ashi as his own flesh and blood, and was even delighted by the fact that he had daughters of sorts.

Aku fondly called Ashi "sweetheart" and himself as "daddy", but that choice of words could have been chosen to further upset Ashi and Jack. However, Aku had no qualms about manipulating his newly revealed daughter into fighting Jack while he lamented that his child had fallen for his sworn enemy. Despite that, Aku's many genocides of countless nations included children as well and Aku had previously targeted a younger Samurai Jack shortly after the subjugation of his homeland while knowing the threat that the son of his former nemesis, the Emperor, would pose to him if he was left unchecked.

After 50 years of battling Jack, Aku's personality seemed to be largely unchanged and appeared to be more mellow, though he appeared to have sunk into something of a depression due to Jack's agelessness, which caused Aku to stop caring about being the ruler of the world. Aku had a more noticeably annoyed and fed up expression on his face and his attitude reflected that: where once before, he would have killed whoever had displeased him, in that state of annoyance. Aku instead got annoyed that the Mud Aliens had dirtied the floor of his lair and told them that he "just had it vacuumed!" and then angrily told them to leave. That also extended to the robots that were sent to kill Jack, as Aku had stopped caring about the new tech that his scientists had created in order to battle Jack and once told them: "And I care, because?". While he claimed at one point not to care about Jack's fate, Aku was actually deeply disturbed by that discovery, as his long experience with Jack had demonstrated that his foe was unlikely to fall into the hands of any of Aku's Minions, which left the two of them in a potentially eternal stalemate. The idea that he and Jack would have to spend eternity fighting had gotten to Aku so badly that he actually split himself into two and had the other half become his therapist in order to do check ups on his mental health.

That depression appeared to have caused a degree of apathy in Aku, or at least unhappy resignation, as Aku apparently knew that the population of Earth was beginning to rebel against his rule, but he was either unable or unwilling to do much about it personally due to having lost track of Jack. Aku's depression also made him avoid contact with others beings from outside his palace in which he made the giant voice recorder in his likeliness that recorded his message that said that he didn't want to meet anyone and asked them to go away. At the same time, Aku also cared less about tributes to him.

Despite that, Aku's simply sadistic tendencies appeared to be largely intact, as he appeared to be quite pleased with himself after he incinerated the Scotsman and destroyed most of the army that attacked his fortress. However, even that tendency appeared to have been reduced to a considerable degree, as Aku appeared to be more nonchalant than pleased during his destruction of the rebel army. After he was confronted by the Scotsman, Aku either completely forgot to kill the Scotsman's Daughters, or simply didn't bother out of disinterest. Additionally, Aku was shown at one point becoming upset with a group of mud creatures who, in presenting him with tribute, had dirtied a recently vacuumed floor. But instead of having the creatures killed or imprisoned as he seemed to do to others in the past on a whim, Aku merely shouted at them to leave.

After he heard of Jack losing his sword from Scaramouche, Aku nearly reverted to his own self and happy to the point of dancing around with Scaramouche. However, after he discovered that Jack had regained his sword, he then angrily blasted Scaramouche into oblivion. During that time, Aku was shown to be cautious enough not to engage Jack in battle head-on and instead relied on controlling Ashi to deal with Jack in order to toy with him as well as cunningly knowing the fact that Jack would try his best to avoid hurting her. At the same time, Aku also lost interest in fighting Jack since he tried to leave after he saw Jack with his sword again and knew full well the result of the fight.

Although he was an absolute ruler of the world, Aku was not above paying bills in order to use services, like when he paid the phone bill that allowed Scaramouche to talk to him or ordered bounty hunters to kill Jack. It was also shown that Aku was courteous enough to hold the phone while he waited for service to respond. Shockingly, in Episode C, Aku was even polite enough to state his absence, not to mention an apology for any inconvenience of not being able to meet Scaramouche in person, though he ended the recording and screamed at the listener to leave.

Appearance
Though Aku was capable of shifting his form into virtually anything that he wished due to his metamorphic body, his standard form after he self-upgraded and adapted to the Earth was roughly a humanoid being with a black body, a green mouth, and a red beard which extended from the bottom of his chin. Aku had six horns, four long and two short, that extended from his head, and his eyebrows were made of red, flickering flame. Aku typically assumes a humanoid form, concealing his entire lower body in a massive, thick robe that sometimes manifested as flames. There is one known instance where Aku removes the robe to reveal his thin legs in "Jack and the Zombies". Aku can stand several stories tall and a deep droning noise was often heard around him when he appeared.

Origin
Long ago in the vastness of space, a great, formless, mindless entity of evil arose. Before it could do harm to the universe, it was set upon by three deities, each one originating from Norse, Egyptian, and Hindu mythologies: Odin (the father of Thor), Ra (the Sun God), and Rama (the seventh avatar of Vishnu the preserver). The three deities fought a fierce battle against the black mass and burned the entity almost completely out of existence with their divine power. However, during the battle, one small fragment of the entity was incidentally cut from the whole by Odin and was never burned away.

Unnoticed by the three deities, that seemingly small fragment floated away from the site of the battle and drifted through space for an untold amount of time, until it eventually, and violently, crashed on Earth during the Cretaceous Period in the Mesozoic Era. It was implied that the fragment of the black mass is the very object that caused the extinction of the dinosaurs, although the crash occurred in prehistoric Japan as opposed to the Yucatán Peninsula by a massive asteroid.

Over eons, the fragment evolved into an ever-growing ominous forest of black tree-like spikes, which surrounded a tar-like pit at its center, that devoured any living thing that dared to enter. Eventually, the forest grew so large that The Emperor (Jack's father) decided to kill the evil at its source. After he was armed with a poison elixir that was given to him by a Buddhist Monk, the Emperor, with his cavalry, rode into the forest. As they rode, the forest began to gradually kill off the Emperor's men and left the Emperor himself as the only survivor. Once he arrived at a black lake in the forest's center, the Emperor doused one of his arrows into the elixir that he was given and fired it into the black lake, with him believing that it would destroy the evil forest.

Unexpectedly, the poison arrow's magic had the unforeseen effect of galvanizing the evil mass into a humanoid form: it gave it intelligence, sentience, and shape-shifting abilities. This entity proclaimed itself with the name of Aku and thanked the Emperor for inadvertently helping him. The Emperor then attacked Aku, but with nothing more than his mundane and mortal weapons, he couldn't inflict any harm upon Aku. Aku then easily defeated the Emperor and strapped him to the side of a tree so that he could watch as Aku began destroying his kingdom and slaughtering his people.

However, the Deities, after they sensed the good in the Emperor, summoned him with the aid of Odin's horse, Sleipnir. After the Deities took the good from inside the Emperor, they then used their powers in creating an Enchanted Sword that was capable of harming Aku. After he was armed with the sword and a magical suit of armor, the Emperor plunged into battle against Aku. In the end, the Emperor was victorious and imprisoned Aku into the devastated wasteland in the form of a jagged black tree. As he was sealed away, Aku vowed that he would one day return. During the battle, The Empress gave birth to a son. After he was determined to learn from the catastrophe, and was aware that Aku would indeed one day return, the Emperor hatched a plan while orchestrating the events that would set Jack on his eventual years of training.

Return
Eight years later, during a solar eclipse, the seal that the Emperor placed on him broke and Aku was released. Aku's first target was the village of the Emperor who sealed him away eight years prior. In a castle, Jack was a young child and his father told him the tale of how he defeated Aku. After the story was done, Jack was left alone, and played with a toy sword. Suddenly, the castle was covered in Aku's shadow. Aku then unleashed a vicious attack on the village. The Emperor then attempted to grab the sword, but Aku captured him before he could reach it. The Emperor told the Empress that it was time to enact the plan they had prepared for. Following the plan, Jack's mother escaped with Jack and the sword. Jack then started on a journey to prepare him both physically and mentally for his confrontation against Aku.

Many years later, a formidably trained Jack returned to find his land devastated and his people, including his father, enslaved: they were forced to harvest the rich resources of their land for Aku so the demon could increase his powers and spread his evil across the entire planet. After he was filled with righteous wrath, Jack quickly slew the Minions of Aku and then went to Aku's Castle to slay him. After a vicious battle, Jack eventually overpowered Aku. However, before Jack could finish Aku off, a desperate Aku then tore open a time portal and flung Jack into the distant future, a future in which Aku was certain that his evil would be spread out all over the world.

The Future
Unknown millennia passed before Jack reappeared into the future. During that time, Aku managed to terrorize or subjugate a majority of the entire world and declared himself the undisputed ruler of Earth. Although he began with demonic servants to carry out his will, Aku later became enamored with mechanical ones since his demonic servants couldn't carry out his tasks fast enough. Aku then recruited a council of Mad Scientists into creating the X-Model. All except X-49 were eventually destroyed before the next generation of Aku's Army was developed: the Beetle Drones. Successors to the X-Models, the Beetle Drones became the model for a series of insect-themed robots which served Aku well into the height of his power and were his standard henchmen.

Hungry for more power, Aku established Earth as a space-faring world and opened his ports to surrounding galaxies in order to plunder or conquer worlds beyond as well. The influx of aliens, who ranged from enslaved species to rough immigrants, transformed Earth into a hodge-podge of dystopian societies that were primarily run by tyrants or gangs. The few bastions for peace and hope typically remained out of Aku's wide field of vision. During Jack's revelation to Ashi, he showed her how Aku had apparently spread the word throughout the universe that criminals were welcomed on Earth, which had made it a safe haven for some of the worst scum in existence. They, in some cases, had decimated occupied settlements that were inhabited by innocent, helpless residents without any scruples. Corrupted agents also made the lives of countless citizens worthless under Aku's regime. Unsavory establishments such as the Dome of Doom and Creature Combat Club were common in the world under Aku.

Aku initially had a habit of watching Jack from afar and stewed over his inability to kill him. Aku used any opportunity to destroy Jack, whether through unleashing his minion armies, hiring bounty hunters, using mystical weapons, clever traps, simple trickery, and other methods in an unending struggle.

Despite being highly feared, hated, and despised by almost all sentient beings in the world or the universe, some beings worshiped Aku as a divine figure.

During his last encounter with Jack, Aku managed to stop him from jumping through the last known time portal and then subsequently destroyed it. Aku then revealed to Jack that he had destroyed all the other Time Portals in existence, which ostensibly ended Jack's quest to return to the past, which also inadvertently broke the seal that Jack placed on Mad Jack. After he reveled in Jack's anger, Aku fled the scene after he transformed three baby goats into monsters, which Jack then butchered in his rage. Immediately after that encounter with Aku, Jack lost his sword, but, as Aku had left moments before, he didn't witness this event.

50 Years in the Future
After he destroyed the last known time portal and eliminated Jack's ability to return to his own time, Aku decided to stop confronting Jack personally. Instead, Aku then continued to send bounty hunters after Jack while he simply waited for him to die of old age and believed that his victory would be assured. However, it later became apparent that Jack's initial time-traveling had halted his natural aging process: it eternally left him at the same biological age as when Aku first sent him into the future. This discovery scuttled Aku's plan and left him at somewhat of a loss as to what to do about his seemingly ageless foe. Ironically, despite Aku's fear of confronting him, Jack never manage to recover his lost sword, which rendered the samurai helpless against any potential attack by Aku. Because Aku had given up attempting to defeat Jack personally, he did not discover that Jack had lost his sword, and none of the bounty hunters who encountered Jack ever managed to report back to Aku alive. Somewhat oddly, though Aku never discovered that Jack had lost his sword, he did somehow learn Jack had grown a beard. During that time, Aku also came to realize, much to his annoyance, that stories of Jack's experiences began to inspire relatively widespread rebellion against him. Frightened of encountering Jack, Aku could do little personally to stop the uprisings and fell into something of a depression. Trapped in an eternal stalemate with Jack, Aku began to develop a degree of apathy even towards his tyrannical rule. He even began to see a Therapist in a sense, split himself into two entities, and talked with himself.

At one point, long after his last encounter with Jack, Aku's Castle was attacked by a large military force, which included an army of Scotswomen who were led by their father, The Scotsman. After he hoped to shake himself out of his boredom, Aku then nonchalantly destroyed most of the Rebel Army himself. After he simply flattened most of his enemies by rolling over them in the form of a giant black sphere, Aku then prepared to destroy the group of Scotswomen, who had been instructed to flee by their father. However, before he could do so, Aku was then confronted by the Scotsman. Hoping to distract Aku, the Scotsman mocked him incessantly for being scared of Jack and consequently losing much of his fearsome reputation. After he endured the Scotsman's taunts for a short time, Aku then incinerated the Scotsman with his eye-beams. However, Aku then quickly became unhappy again due to the Scotsman mentioning Jack, returned to his castle, forgot to kill the Scotsman's Daughters, and missed the Scotsman's return as a ghost. Aku also later received a phone call from the severed head of the assassin, Scaramouche, who learned that Jack's sword was missing and hoped to inform Aku. However, random circumstance and Scaramouche's undiplomatic nature conspired to prevent Aku from learning of Jack's plight.

Eventually, however, Scaramouche managed to reach Aku and reported the status of Jack's sword: unknown to Scaramouche, that the information arrived too late. After Scaramouche told him, Aku then angrily pushed down hard on Scaramouche's head and asked him if he was sure. Excited with the news, an immediately reinvigorated Aku confronted Jack for the first time in decades with a full-bodied Scaramouche, only to discover that Jack had already recovered his sword. After he destroyed Scaramouche in anger, Aku casually attempted to leave the area until he noticed a familiar smell that came from Jack's companion, Ashi. After he suddenly remembered the time that he had visited the Cult of Aku and offered them some of his essence, Aku quickly deduced that Ashi was his biological daughter and then used the essence inside her to control her into fighting Jack. Aku casually remarked to a giant robot corpse how his (last remaining) daughter had fallen in love and run off with his mortal enemy. After he was already bored with Jack's attempt to free her, Aku then simply tossed the robot onto them before he possesses Ashi with a new bodysuit in his likeness. When Jack couldn't bring himself to kill Ashi and surrendered, Aku then ordered Ashi to stand down, claimed Jack's Sword for himself, and relished in his victory..

Demise
In the Series Finale, Aku captured Jack, stole his sword, broadcasted his victory to everyone in the world, if not the universe, and, once again, relished in his victory. Aku then prepared to kill Jack in front of the whole universe, but was confused as to how he should kill him. After a period of indecision, Aku decided that it was best for Ashi to kill Jack. As Ashi prepared to kill Jack, all of Jack's allies soon arrived and fought Aku and his forces in a grand-scale battle while Jack dealt with the possessed Ashi.

Aku found amusement in the army's attempts to save Jack: while they may have been able to fight off Aku's forces, Aku himself was nearly untouchable. Eventually, Ashi freed herself of Aku's possession because of Jack's love for her, but also retained his powers. After Ashi realized that, she quickly took Jack's Sword back, and, before Aku could stop them, she warped Jack and herself back to the past with her own time portal. The last time that the Future Aku was seen he uttered his last words: "Oh no...." with an extremely worried look on his face and knew that his end would soon come.

In the past, the events of the first episode played out: Jack had just defeated and weakened the Past Aku, who promised that he would destroy Jack in the future, opened up a time portal, and sent Jack into the future. However, Past Aku was soon caught off guard when Jack and Ashi arrived in the same spot where he was cast in the future, ten seconds after it happened, which confused the Past Aku as to how Jack was "back already" and was unaware that the Jack who stood in front of him had spent fifty years searching for a way back to the past. Jack then rushed at Past Aku and attacked him without mercy.

Jack made short work of the weakened the Past Aku, and sealed him inside his katana again. That time, however, Jack used his sword to destroy the Past Aku once and for all: Jack plunged his sword with the Past Aku still inside into the ground, which then caused the Past Aku's Castle to explode, took Past Aku with it, which prevented the rise of Aku and spared both space and time, the past, present and future and the universe from his tyranny forever.

Legacy
Tragically, since Ashi was Aku's Daughter, Ashi "passed away" before she and Jack were married. This may or may not have happened to anyone and potentially everyone else from the future, as Aku's long-term conquest had shaped all their lives in some way or another; if they did exist in the new timeline, most would be very different people living in likewise radically, albeit positively, altered circumstances. Despite these implications, Aku's destruction meant that all the evil that he had inflicted was undone, thus sparing future generations from life under his tyranny.

Ironically, it was shown that Aku still, albeit indirectly, was capable of hurting Jack emotionally when his past destruction affected Ashi's existence since she was his daughter.

Battle Through Time
In a desperate, last-minute attempt to prevent his destruction at the samurai's hand, Aku transports Jack into a time pocket, a rift of time and space that is not affected by the main timeline and under the demon's complete control, forcing Jack to relive many of the challenges he has faced before in familiar locations. Aku also corrupted the royal family's kamon crests with his black magic and scattered them throughout the world.

Fighting through various robots, demons, and bounty hunters, as well as Ashi and her sisters again, Jack cuts through the remains of Aku's armies with the aid of Scotsman and his daughters, Da Samurai, and Sir Rothchild and engages in a final showdown with his hated nemesis within his fortress.

Finally defeating Aku, the rift of time the demon created begins to fade away as the portal back to Ashi and the past opens back up for Jack. Expressing disbelief that his final plans have failed, Aku refused to accept defeat just before Jack delivers the final blow,

After Aku's defeat, the time pocket collapses on him and Jack slices through him. Jack is reunited with Ashi as both are transported back to the past where Jack finally destroys Aku, alongside his fortress, undoing all his evil in the future. It is unclear whether the future Aku's onscreen defeat before the final time-jump actually killed him in the same capacity as his past demise, but if not, the alternate ending where the future is not erased would imply that he is now permanently trapped in his own created pocket dimension.

Abilities
Aku was well known for being one of the most powerful characters in the series. He had a large range of powers and capabilities that made him almost unstoppable. Aku was a supernatural demonic entity which Jack described as the personification of primordial evil, was one of the most powerful beings in the series, and there were few who could oppose him.
 * Near-Immortality: As a supernatural being, Aku was ageless and nearly immortal. He required no sustenance and was not harmed by mortal means. Only the power of righteous spirits or divine weapons like Jack's Sword, or divine entities, were capable of doing severe harm to him
 * Shape-shifting: Aku could change into virtually any form that he desired, from a giant dragon to a small insect, or even a beautiful woman. Aku was able to seamlessly change his size, liquefy himself, or stretch and expand his body. He could even replicate into clones of himself to be in numerous places at once and his mind inhabited numerous bodies. At one point, Aku even manifested a second version of himself who acted as a psychologist. In a way, Aku performed talk-therapy on himself. He typically changed into animal forms during battle, such as a scorpion or an octopus and adapted to the situation. On one occasion, Aku also transformed into a huge, amorphous mass of darkness that greatly resembled the evil entity that he had previously once been/was spawned from and altered parts of himself at will.
 * Supernatural Physical Abilities: Aku could alter his physical capabilities to virtually any level that he needed or wanted due to his magical shape-shifting abilities. Aku manifested superhuman strength, speed, endurance, and senses. No parameters or upper limits were established that regarded those capabilities.
 * Regeneration: While Aku was completely resistant to most forms of attack, he was not invulnerable; items such as Jack's Sword or magic such as divine energy could damage the substance from which he was made of. However, Aku was able to regenerate to a large degree, even against attacks such as those. These sort of assaults tended to create large, burning holes or gashes in Aku wherever he was struck, which he could close back up with effort. However, his ability to regenerate in those situations was limited. In many of Aku's confrontations with Jack, the damage that was caused by the sword whittled away at his overall mass and his ability to regenerate in the short term, until it tended to leave him as a very small animal of some sort, such as a frog or a mouse, at which point further attacks would have presumably either sealed him away as Jack's father did, or killed him as Jack intended to. Given time however, Aku always restored himself without being any worse for wear. Aku was also observed to succumb to physical pain that involved blunt trauma of equal mass in relevance to the size of his form at any given time, although he was shown to quickly recover from such injuries.
 * Dark Magic: Aku was an all-powerful wizard who had vast supernatural powers at his command:
 * Happy Aku laser.pngEye Beams: One of Aku's most commonly utilized attacks, that ability tended to manifest as beams of white or red light that typically incinerated the objects that it made contact with. It could be used either as continuous beams of light, or as staccato bolts of energy. Aku had used that ability in numerous battles with Jack, and also used it to destroy the majority of Jack's past kingdom. Aku could also harmlessly teleport beings to places of his choosing through that power. The beams could also slice through objects like a plasma torch, or caused them to explode.
 * Aku also used a variation of that ability to restore or recreate whatever he chose: he restored Scaramouche's body with them.
 * Remote Viewing: Using mystical forces in his lair, Aku could create images on the walls in order to view whatever he wished. Aku tended to use that ability to simply watch Jack travel while he stewed in his unhappiness at being unable to kill Jack.
 * Teleportation: Aku used that often for quick appearances or escapes, and to appear before those that he had business with, such as the Imakandi.
 * Elemental Control: Aku could magically project and control the elements of the physical world. Those abilities included breathing and projecting streams of fire from his body, manipulating the earth itself, conjuring thunderstorms at will, or emitting waves of sonic force. By combining fire breath with his eye beams, Aku could also project beams of electricity.
 * Telekinesis: Aku was shown the ability to manipulate objects through focus alone, even from far away distances. While he used that ability, Aku's eyes tended to flash white.
 * Necromancy: Aku was shown to be capable of animating countless dead bodies and bending them to his commanding will.
 * Precognitive Dreams: On one occasion, Aku was shown to be capable of receiving premonitions of his own future through his dreams, which he could then act upon to try and prevent or change them.
 * Possession & Infection: Aku could use small portions of himself to infect others with his evil. The only time that this was seen was when he incidentally spat up a tiny portion of himself at Jack, which, over the course of a day or so, possessed Jack and gave him the appearance and personality of Aku. On a related note, Aku could also use portions of himself to give power to machinery, as he demonstrated by doing so with the Ultra-Robots. That ability could also work on Aku's biological offspring, since they already had his essence and were a part of him.
 * Interstellar Travel: Aku was capable of interstellar travel, well beyond the speed of light.
 * Time Travel: That was the very ability that Aku had used that sent Jack into the future at the beginning of the series, though he only used that once and it was a one way portal forward in time. However, due to its side-effect, Jack did not age even after 50 years in the future.
 * Object Materialization: The ability to create matter and materials out of nothing: Aku once used that ability to conjure treasures in the presence of the Imakandi. Aku also used his eye beams and created a new body for Scaramouche.
 * Corruption: One of Aku's most powerful abilities. Using dark magic, Aku could mutate normally harmless beings into monstrous versions of themselves. During his last known encounter with Jack, Aku used that ability and transformed three small rams into monsters in order to fight Jack. It was also shown that if the corrupted creature died, the spell was broken and the creature transformed back to its original form. Aku also used that power to curse the Well of King Ozric and then later corrupted Jack through his supposed illness. Aku was also able to infuse that power into techno music to corrupt teenagers in "Jack and the Rave". This power extended to the fact that Aku could create life in a way, as shown when he gave the High Priestess a sample of his essence that was originally intended in the use of worship to presumably conceive the Daughters of Aku, as well as enabled him to control or corrupt any and all of his offspring into his likeness, who were complete with supernatural powers.
 * Combat Skills: Despite never having been shown to have trained at all in any form of Martial Arts, Aku was a very skilled practitioner in hand-to-hand combat. Though not a match for Jack, Aku was at least capable of defending himself reasonably well against Jack during their duel, while he limited himself to human physicality. Aku was also shown to be a fairly skilled swordsman: In Episode XXX: Jack and the Zombies, Aku stole Jack's Sword and was able to force Jack (who was armed with a sword and a shield) into a defensive posture during a bout of swordplay. However, it should be noted that on that occasion, Aku was not limited in the scope of the powers that he could employ.

Weaknesses
Despite his powerful abilities, Aku had a few weaknesses:
 * Color Scheme: Aku could not change the color of his body, meaning that regardless of the form he took, his color scheme would remain black, red, white, and (sometimes) green. While not particularly problematic with regard to combat, that could make disguising Aku difficult (though he still fooled Jack numerous times with his disguises, as Jack tended not to notice Aku's consistent color scheme. The one time Jack did see through Aku's disguise, it was because of Aku's own personality, rather than his glaringly obvious color scheme).
 * His Reflection: Aku's own reflection revealed his true form, no matter what he shape-shifted to look like.
 * Divine Power: While Aku could not be harmed or killed by conventional means, those with divine power such as Jack's Sword, Odin's Gungnir, Rama's Sharanga, and Ra's Crook were able to do so. The Goddess of Water and her fellow elementals were able to harm or defeat Aku. According to Rama, Aku could also be vanquished by "The strength of the human spirit and the virtue of human righteousness" since he was the incarnation of evil. Because Jack's Sword was the only physical weapon on Earth that was able to destroy him, Aku was reluctant to confront Jack head-on.
 * Illnesses: Despite his nature as an unholy demon, Aku was still susceptible to the equivalent of human illness, shown when he came down with a severe cold in Episode XLIII. This forced him into a perpetual case of lethargy with a severe cough, and what seemed to be congested sinuses. His condition was so poor that he quickly gave up his current attempt on Jack's life, transforming into a simplistic pair of wings and flying off while saying "I don't feel good."
 * Righteousness: The power of righteousness of any living creatures were able to vanquish Aku. The Scotsman's music imbued with the power of his spirit was able to affect Aku at some degree and even nullified his attack. Ashi's own purity/strength of spirit were able to release her from Aku's grasp and gain control of his powers as a hybrid. In the case of anyone else that Aku corrupted and infected, his essence was purged from their bodies. Odin, Ra, and Rama forged Jack's Sword from the very same power.
 * Time Travel: Despite being capable of opening a time portal to the future once, for some reasons, Aku was unable to travel through time. That was seen when Ashi opened a time portal to transport herself and Jack back to the past, but Aku didn't open his own time portal to give chase and prevent them from reaching the past and save himself: instead, Aku became fearful as he was aware that his death was coming.
 * His Own Power: Aku's power could be used against him by any of his hybrid offspring with a strong and righteous spirit. When Aku corrupted Ashi and turned her into his unwilling minion, she inherited some of his powers after she broke free. Ashi aided Jack by transporting both of them into the past by producing a time portal: That allowed Jack to vanquish Aku for good and led to his downfall.
 * Sadism: Being the personification of evil, Aku's sadistic tendencies will always get the best of him to point of impracticality. More than once, he made a deal with his subjects and every time they comply with their own part of the deal, Aku will always go back on his word, mostly for his own amusement, causing them to inevitably turn against him and help Jack in stopping Aku's plans. Furthermore, any time he has Jack at his mercy, he wastes time by trying to find creative ways to execute him rather than just killing him right away. This especially comes to a head during the final episode where rather than executing him immediately (or even destroy Jack's sword, the only weapon that could harm him), he chose to publicly broadcast it on a live television before wasting time trying to think of ways to kill him, giving Jack's allies time to arrive at his lair and distract him long enough for Jack to escape and Ashi to break free of his control and go back in time to vanquish him once and for all.

Known Forms

 * Bird: (Aku used that form mostly to escape) used in Episodes I, XIV, and others
 * Bat: used in Episode XLVIII
 * Weapons (just hands or other parts of his body): used in Episodes XXX, CI, and others
 * Scorpion: used in Episode I, XXX, and also shown in opening titles
 * Gorilla: used in Episode I
 * Billy: used in Episode I
 * Kraken: used in Episode I but also shown in beginning opening titles
 * Squid: used in Episode VIII and was briefly seen in Episode XXXVIII
 * Manta Ray: used in Episode IX
 * Spiked Tubeworm : used in Episode IX
 * Cobra: used in Episode XII
 * Dragon: used in Episode XIII
 * Chinese Dragon: used in Episode XXX
 * Praying Mantis: used in Episode XXX
 * Amorphous Mass of Darkness: used in Episode XXX
 * Mouse: used in Episode XXX
 * Frog: used in Episode XXXIV
 * Fish: used in Episode XXXIV
 * Giant Spider: used in Episode XXXVIII
 * Winged Dragon: used in Episode XXXVIII
 * Army: used in Episodes XXXVIII and CI
 * Human: used in Episode XLVIII
 * Therapist doppelganger: used in Episode XCIII
 * Giant Cannonball: used in Episode XCVI
 * Spiky rain cloud: used in Episode CI (future)
 * Giant rhinoceros beetle-like form (possibly the limits of how much he has of himself left): used in Episode CI (past)
 * Pac-Man ghost-like form (possibly the limits of how much he power has remaining): used in Episode CI (past)

Ikra
One of Aku's aliases, Ikra was just one of several forms which Aku assumed in order to travel closely with Jack. Using his shape-shifting abilities, Aku changed himself to the appearance of a young woman with green skin, black hair, and a black dress. He/She then traveled with Jack across the desert and battled many dangers together.

Under the guise of Ikra, Aku and Jack formed a close bond (at one point, Ikra even saved him from drowning in quicksand). Ikra told Jack that her father, like Jack's, had fought with Aku, lost, and was forced to spend eternity trapped in a ring of fire. Ikra told Jack that she was on a quest to find a magical jewel in the desert which was powerful enough to free her father. When Aku revealed himself as having been Ikra the whole time, he mocked Jack for having believed the story about her father.

The Hermit
The Hermit was another of Aku's aliases, he was just one of several forms that Aku assumed in order to travel closely with Jack. Using his shape-shifting abilities Aku changed himself to the appearance of an old cranky hermit with green skin, white hair, and a black robe. He then traveled with Jack in order to find the Gems of Cronus. Aku looked for one gem after another, in order to resurrect Cronus.

Unlike with Ikra, Jack saw through the deception and ultimately turned the tables on Aku. In the ensuing battle, Jack defeated and heavily injured Aku, which then forced him to retreat.

Quotes
Season 1-4 The Shadow of Aku Season 5 Battle Through Time
 * "You! Thank you!"
 * "But it was your poison arrow and your hocus pocus that set me free!"
 * "Fool! Nothing of this world can harm me. For I am Aku, the Shogun of Sorrow, the Deliverer of Darkness, your new master. And you will bow to me."
 * "What is this? What form of insect is this? BWAHA! It is you."
 * "Have you learned nothing? Your mortal blade cannot harm me. AAAAAAAAH!!"
 * "How could this be?!"
 * "BAH!"
 * "I WILL RETURN!!"
 * "Once again, I am free to smite the world as I did in days long past."
 * "Who dares to summon the Master of Masters, the Deliverer of Darkness, the Shogun of Sorrow, Aku!?"
 * "Fool, no mortal can hurt the great Aku."
 * "MUHAAAAAAAAA!!! That sword. I remember that blade. I recognize your blood. You are the son of the fool who imprisoned me those many years ago. No matter, neither he nor the sword had the power to slay me forever, and neither do you!"
 * "You might have beaten me now, but I will destroy you in the future."
 * "I disagree."
 * "Do not worry, samurai, you will see me again. But next time, you will not be so fortunate."
 * "I know of your plight, Vadaquian, for you see, I am he who has taken your water and the riches within them."
 * "The boy will return. He will learn proper respect for Aku in The Pit of Hate."
 * "You will be allowed. The oceans of Aku will be your new home. But you will pay homage to me by constructing statues in my likeness. Once a month, a monolithic tribute will rise from the depths of the ocean to remind all who is the master of this world. Now begone!"
 * "What information can be considered great for the immortal Aku?"
 * "What impertinence is this? Show me the fool!"
 * "HA! HA! HA! HA! So fate has arrived. Many years have gone since that day. And now my formidable foe, you will pay for my pain in the past with your pain in the future. HA! HA! HA! HA!"
 * "He is stronger than I remember. But no matter. For you see, little Samurai, the world is mine! My eyes and ears are everywhere, nothing you do will go unseen! Quest as you may, but we will meet again when I see fit, in a time and place of my choosing! And it is I who shall put an end to the war started in that age long past, Samurai Jack! Bwa-ha-ha-ha!"
 * "Fool!"
 * "Useless bounty hunters! Is there no fighting style that can defeat his?... Yeeeeees. No fighting style can defeat his."
 * "MAAAH! The sword!"
 * "This is not over, Samurai! We shall meet again!"
 * "Who dares to summon... Oh, it is you."
 * "For eons I have terrorized this land. Every miserable creature trembled at the mere mention of my name. The pitiful people fright before my awesome power. But now, I am openly mocked by these measly urchins. Tales of the Samurai's heroics have spread through the world like a virus, but I will cure the world of this plague of hope. I will unleash such evil that even the most innocent soul will be consumed by terror!"
 * "The spear struck the beast, transforming him into... beef jerky!"
 * "Once upon a time, there was a little girl with an adorable red cape and GREAT FLAMING EYEBROWS, who was beloved by all."
 * "The wolf attacked Lil Red Hood, not knowing that Lil Red Hood had laser eye beams, great combat skills, and a powerful uppercut that freed Lil Red's grandmother from the evil bowels of the wolf."
 * "Not so fast, Samurai!"
 * "Your efforts are in vain, Samurai! This gateway into the past is forever... huh? Beyond your reach!"
 * "Poor Samurai. Once more you failed! As you lie smashed and defeated, so lie your hopes of going home. A-ha ha ha ha ha! Till we meet again."
 * "Samurai fool! Your efforts are in vain again. This gateway to the past is once more beyond your... reach? You can fly?!"
 * "YE-YEOW!! The sword!... The Samurai!"
 * "As far as the eye can see, the land is desolate and full of despair. Shadows crawl across the Earth and block out the light. Darkness oozes from every crevice. Hope has been eradicated. Only terror reigns. Yet, there is one that mocks my omnipresent evil with his existence. He possesses a sword which could destroy me. They call him... Samurai Jack!"
 * "Despite my efforts, he has not yet been destroyed. But now I, Aku, dark lord of all darkness will make the final move and annihilate Samurai Jack forever."
 * "From deep within The Pit of Hate, I summon: Demongo!"
 * "You are one of my most powerful Minions. You possess the ability to steal the essence of the mightiest of warriors or the deadliest of beasts.You have never failed me."
 * "Find Samurai Jack! Destroy him, and enslave his essence!"
 * "You have failed me, Demongo."
 * (on forgiving Demongo) "Hmm..... No!"
 * "Once again, the saga continues."
 * "Samurai, samurai. Why won't you DIE!?"
 * "Foolish, unknowing, innocent samurai. Little do you know that the path l have chosen for you will lead you to your doom!"
 * "You can run but you cannot hide 'cuz I can smell your blood!"
 * "I will get you yet, Samurai!"
 * "Vamenos, muchacho!"
 * "Even without deception, without mystic weapons, you will fall against the powers of Aku!"
 * "Bah, I say. BAHH!"
 * "Now let us test your enchanted steel against the power of the Titans!"
 * "Bye bye, samurai."
 * "No, I will not fight you today. Oh, I don't feel good."
 * "I seek to foil the samurai! To destroy his dream of returning home and to destroy all who stand in my way!"
 * "You worthless, wrinkled grub! I'll have you for dinner, you worm! I'll eat every last monk in this hole! I'll devour you all just as I had consumed the samurai! HA!! HA!! HA!! HA!! HA!! HA!!"
 * "I am Aku, this world is Aku, and everything in it is Aku!"
 * "BWAHAHAHA! Yes, I can hold. Yes, I'd like to place an order for delivery. Aku. I think I'm in the computer. Yes, that's it. I'd like a large... What? Huh? Extra thick! 30 minutes or it's free? Excellent! BWAHAHAHA!"
 * "STUPID BOUNTY HUNTERS!"
 * "Do it yourself!? Yesssss."
 * "Yes. It is I, Samurai Jack. How incredibly observant you are."
 * "Aw, put that thing away, samurai. We all know what's going to happen. You'll swing your sword, I'll fly away, and probably say something like "I'll be back, samurai!", and then I'll flutter off over the horizon and we won't see each other for about a week, and then we'll start the whole thing all over again."
 * "I'll be back again, Samurai, you'll see! HAHAHAHAHA!!! See what I mean?"
 * "Tsk, tsk, tsk, tsk. Coulda, shoulda, woulda. It's all part of life's sweet sorrow. You're so lucky, samurai. Most of us have to live with our mistakes, but you get to DIE by yours!"
 * "Ha! Ha! Ha! I told you to wait! Now I will return to perpetuate my evil on the face of the earth! But you, Samurai... you will be defeated!"
 * "What? Who is that?"
 * "WA! HA! HA! HA! HA! Whew! That was close! I didn't think you'd get here so fast."
 * "Fool!"
 * "Oh, fun fact: That was the last remaining time portal in existence."
 * "Woo, so angry. Be careful, Samurai, so much stress will give you a heart attack. Oh, what am I saying? Please continue, never mind what I say."
 * "Oh-ho! Not so fast, samurai! I know better than to mess with that sword! But before I go, I leave you someone to play with."
 * "Stop! Look at what you're doing. You're getting yourselves all over the floor. I just had it vacuumed. Out! Out! Get Out!"
 * "And I care because?"
 * "Oh! That was the old Aku. This is a new Aku. And he really doesn't care about the pathetic Samurai who wanders around like a mad fool. Haha! It's hilarious, really. Look, I'll tell you what... You wanna destroy him? Go ahead. Who cares? I certainly don't. Not one bit at all."
 * "So, tell me what's been bothering you."
 * "Well, you see, doc, it's been over fifty years already."
 * "It's been that long?"
 * "Yes, you see, that's the actual problem. Once I e-rad-i-ca-ted all the Time Portals, I thought I would just wait it out and then, the Samurai..."
 * "We don't say his name here, it is a safe place."
 * "Yes, sorry, doctor. Well, I-I just assumed that eventually over time, he will just... (both): DIE!"
 * "But he hasn't even aged. I mean like at all! He just grew that stupid beard, and looks like he'll be here forever! I... I just don't know if I can handle that."
 * "Yes, it seems that the initial time travel has affected the aging process. It's quite the conundrum."
 * "Yes, what is that again?"
 * "Just a confusing or difficult problem."
 * "Yes, problem. I wished there is someone who can dispose of my problem."
 * "(both): Yes, one can hope."
 * "Would somebody please... STOP ALL THAT NOISE?!"
 * "Perhaps annihilating this scum will break me out of my... malaise."
 * "Better to make it a COMPLETE annihilation."
 * "I'm sorry old man. I think you're lost."
 * "Ah, why did he bring up the Samurai? Ughhh!"
 * "You are now hearing the voice of Aku! Unfortunately, I will no longer be available for any more appointments. I'm sorry for any inconvenience this may have caused you. NOW GOOOOOOOO!!!!!"
 * "What joy!"
 * "Oh, yeah! Doo-doo-doo-doo-doo-doo-doo"
 * "But you're probably saying to yourself: (Perfectly mimicing Jack's voice)  'Why? Why now for a sudden reunion?' "
 * "Well, a little birdie told me... "
 * "I smell ME!"
 * "Yes, I smell me inside of her."
 * "But how could that be? I never... oh wait, there was that one time."
 * "Not bad. Yes, an attractive replica, but it pales to the original. Here!"
 * "Worship me, Daughters of Aku!"
 * "So she must have... Drank it? And then..."
 * "Here you are, a TRUE Daughter of Aku!"
 * "Of course it is, sweetheart. You wouldn't let your daddy get hurt by that bad old samurai?"
 * "I mean, you try and raise them right, then they run off with your mortal enemy! What's a dad to do?"
 * "Sweetheart, you have to bring out your best to defeat him, and your best is ME!"
 * "Long ago in a distant land, I, Aku, the shape-shifting master of darkness, unleashed an unspeakable evil! But a foolish samurai warrior wielding a magic sword stepped forth to oppose me. Before the final blow was struck I tore open a portal in time and flung him into the future, where my evil is law! Now, the fool seeks to return to the past and undo the future that is Aku! Not!!! Because after all these years, I have captured Samurai Jack and the sword!!"
 * "To all those fools who dare oppose me, your hero is dead! YOUR HOPE IS DEAD! I am the one true master! Let this be a lesson to all! Time to die, Samurai Jack!"
 * "Ha, ha, ha, ha! You're nothing but insignificant insects to Aku! And insects get SQUASHED and exterminated!"
 * "Flying monkeys!?"
 * "A Giant Stone Samurai? Really?"
 * "Is he dead?"
 * "How dare you talk back to your father!"
 * "Yes, I am!"
 * "...Oh no."
 * "HUH? YOU'RE BACK ALREADY?!?!"
 * "NO, WAIT!" (Aku's last words)
 * "ARRRRGH!!!"
 * "Poor, little Samurai..."
 * "You thought you could return to the past and destroy me?! HAAAA!"
 * "I have cast you down into a place with no future or past. A place between time."
 * "Here, things you know, or think you know, may not be what they seem and I control your fate. And the only hope of escape is through your death. HAHAHAHAH!"
 * "AAAHAHAHA!"
 * "You still think you can escape from this place and defeat the mighty Aku?!"
 * "Ahhhh ha ha ha ha! Fool! Let's see if you ALONE can withstand the power of my army!"
 * "ARRRRGH!!! ATTACK!!"
 * "Destroy the Samurai!"
 * "You may have bested those I put before you, but NOW you will know the true meaning... OF PAIN!!!"
 * "What is this?!"
 * "Gaaaa! Noooo!!"
 * "Curse you, Samurai Jack! I will find a way to destroy you! You will not succeed!"
 * "This is not over..." (Aku's last words)

Trivia

 * In the first episode, The Beginning, Aku's voice was low pitched, which made him seem more sinister. However, in later episodes, Aku's pitch went higher.
 * In the early episodes of the show, the red color of Aku's flame extended to a red outline around his eyes.
 * Aku's design experienced a number of inconsistencies across all of Season 5's episodes. Such inconsistencies included:
 * His hands having 5 fingers instead of 4 (although 4 fingers were still shown at times)
 * The top green line between his eyes missing.
 * Expanded red lining inside his mouth.
 * Aku's appearance is most likely that of an Oni, a yokai, supernatural demon, ogre, or troll in Japanese folkland. For he consists of many horns and is colored red and green on the face while the rest of his body is black.
 * Aku was parodied several times in Duck Dodgers, a Warner Brothers-produced cartoon that starred Daffy Duck that ran alongside Samurai Jack's original run. In the show, Mako Iwamatsu voiced "Happy Cat", a loud and obnoxious cartoon cat with a large amount of merchandise that was showcased throughout the show. The Happy Cat Alarm Clock that was used by Dodgers featured Mako's voice, used Aku's distinct laugh and voice. In the episode "Samurai Quack", a parody of Samurai Jack, Aku was recreated as "Achoo", a combination of Aku and Happy Cat.
 * Many of Aku's sudden movements were accompanied by the sounds of creaking wood. That was presumably because of Aku's body was created from the black trees that he originally took the form of.
 * The Scotsman insultingly called Aku a "Tree Ogre".
 * Although he was immortal, Aku still required sleep: Aku was shown waking up from a bed in Episode XCIII.
 * After the announcement of Season 5, Aku's line of "Extra thick!" from Episode XLVII became a popular Internet Meme.
 * Aku was voiced by the late Mako Iwamatsu for the show's original run. He was known for portraying such characters as Splinter from the 2007 Teenage Mutant Ninja Turtles Film, and General Iroh from Avatar: The Last Airbender.
 * As Mako passed away in 2006, any speaking roles by Aku following would have been taken up by other actors. In FusionFall, Aku was voiced by Greg Baldwin (who, incidentally, was the one who replaced Mako as the voice of Iroh in both Avatar and its spinoff series, The Legend of Korra), and Aku was voiced by Fred Tatasciore in Punchtime Explosion and Punchtime Explosion XL.
 * Interestingly, a storyboard sneak peek of Season 5 had Genndy himself attempting to imitate Aku's iconic voice. However, as it was an animatic, it was not uncommon for the person pitching the scene to do all the voices themselves as placeholders.
 * Later on, it was confirmed that Greg Baldwin would voice Aku in Season 5. Baldwin's interpretation of Aku was a mimic of Mako's original version, while he incorporated the pausing mannerisms of German actor, Peter Lorre.
 * Aku, throughout the series, balanced between being a truly threatening villain and a villain who was designed to make the audience laugh. In more earlier episodes, Aku was a fairly serious and ominous antagonist, who lacked a lot of the dark sense of humor that characterized him later on.
 * Aku shared some similarities with Hexxus, the main antagonist of the film FernGully: The Last Rainforest:
 * Both were evil, charismatic beings, who were made from an amorphous dark substance.
 * Both were initially trapped inside a tree, but were set free by different means (Aku with a solar eclipse, Hexxus via deforestation).
 * Both represented destruction of the environment to a dangerous degree.
 * Despite his comedic tendencies, Aku was easily one the most cruel and immoral Samurai Jack Villains: he destroyed or enslaved entire nations, tortured innocents for fun, starved Jack's father (and possibly many other slaves of his empire) to death, committed genocide on a daily basis, sent millions to work in labor camps presumably until death, and took away the free will of everyone across the universe, merely because the suffering of others amused him. Of course, that was actually very fitting, as Aku was the embodiment of all that was evil and thus, was incapable of having any redeeming qualities.
 * Ironically, it was Aku himself who provided Jack with the means to return to the past when he possesses Ashi and granted her his powers.
 * The word 'Aku' can also be found in egyptian hieroglyphs, where it means "a god or animal in the Tuat (the realm of the dead)". Also, the primordial dark entity from which Aku comes from bears striking resemblance in behavior and concept to the Egyptian deity Apophis, the embodiment of chaos and a god-like monster that's always hungry due to being incomplete and that swallows everything in its path to avoid ceasing to exist.
 * In the Brazilian dubbing of the show, Aku's name is changed to Abu. The reason was because, phonetically, 'Aku' sounds similar to the Portuguese pejorative word for anus.
 * A Japanese goblin emoji that resembles Aku is seen among the emojis dancing at the end of the 2017 Sony Pictures Animation film The Emoji Movie.

Appearances

 * Episode I: The Beginning (First Appearance)
 * Episode II: The Samurai Called Jack
 * Episode III: The First Fight
 * Episode IV: Jack, the Woolies, and the Chritchellites (Cameo)
 * Episode VI: Jack and the Warrior Woman (Ikra)
 * Episode VIII: Jack vs. Mad Jack
 * Episode IX: Jack Under the Sea
 * Episode X: Jack and the Lava Monster (Cameo)
 * Episode XII: Jack and the Gangsters
 * Episode XIII: Aku's Fairy Tales
 * Episode XIV: Jack Learns to Jump Good
 * Episode XVIII: Jack and the Ultra-robots
 * Episode XXII: Jack vs. the Five Hunters
 * Episode XXIII: Jack vs. Demongo, The Soul Collector
 * Episode XXX: Jack and the Zombies
 * Episode XXXI: Jack and the Scarab
 * Episode XXXIV: Jack and the Swamp Wizard (The Hermit)
 * Episode XXXVI: Jack, the Monks, and the Ancient Master's Son (Cameo)
 * Episode XXXVII: The Birth of Evil, Part 1
 * Episode XXXVIII: The Birth of Evil, Part 2
 * Episode XL: Jack vs. the Ninja
 * Episode XLII: Samurai vs. Samurai
 * Episode XLIII: The Aku Infection
 * Episode XLVII: Jack and the Flying Prince and Princess
 * Episode XLVIII: Jack vs. Aku
 * Episode XLIX: The Four Seasons of Death (Vision)
 * Episode L: Tale of X-49 (Flashback)
 * The Shadow of Aku
 * Episode XCII (Voice)
 * Episode XCIII
 * Episode XCVI
 * Episode XCVII (Voice)
 * Episode XCIII (Flashback)
 * Episode C
 * Episode CI (Last Appearance; Death)
 * Samurai Jack: Battle Through Time

Appearances in Other Media

 * Aku was featured frequently in Cartoon Network commercial bumpers from 2001 to 2007.
 * Aku made a brief appearance in the intro to the short-lived programming block, Friday Nights. He could be seen early on standing in the city and rivaled a few skyscrapers in height.
 * Aku appeared as an unlockable Nano character in the Cartoon Network MMO, FusionFall. That was his first speaking role since the passing of his previous voice actor, Mako Iwamatsu. Aku was voiced by Greg Baldwin.
 * Aku appeared in both the handheld and console versions of Cartoon Network Punchtime Explosion as a boss character. Aku was a playable fighter in the console version as well. Aku was voiced by Fred Tatasciore.
 * Aku made multiple background appearances during Cartoon Network's 20th Anniversary Celebration.
 * Aku was a major villain in the IDW comic series, Super Secret Crisis War! in which he, Vilgax, Mojo Jojo, and Mandark teamed up.