The Omen

"''Great warriors of past, I welcome you. This samurai has failed his purpose, and has accepted his fate."

The Omen is a mysterious spirit of death who frequently haunts Jack. He resembles a ghostly black silhouette of an armored samurai with glowing eyes riding on a horse, surrounded by an ominous green fog.

Upon revealing himself, he appears to have no visible face and a noose around his neck. He also has a deep, dark voice. It is later revealed that the reason he haunts Jack is because he has neglected his purpose as a samurai, and insists that he commit ritual suicide by seppuku to atone for his failure. The Omen is the tertiary antagonist of Season 5.

Background
Very little is known about the mysterious spirit, except that he stalks Jack at various points; it can be noted that he always appears whenever Jack has feelings of intense guilt or doubt in himself.

The Omen first appears on the other side of a stream, after Jack hallucinates seeing his parents and multiple corpse-like people. The area becomes black and the rider appears with a ghastly green background, shocking Jack as he glares menacingly at him. The Warrior appears again that night, as Jack is tormented by a hallucination of his Father in flames, after which his signature horse whinny alerts Jack to turn around and see the Omen again, imprinted on a rock. The next day, in the middle of Jack's battle with the assassin Scaramouche, the spirit appears on a nearby hill, watching Jack's hallucination of the city's slain children. (Episode XCII)

Later, the Omen appears a fourth time as Jack hides inside the parts of a previously destroyed Beetle Drone. As one of Jack's hallucinations of himself pleads with him to join his ancestors, Jack turns to look through the crack of the Beetle Drone's shell, only to see green mist surrounding the area and the Omen staring at him. Jack manages to see past the Omen and his misty fog, therefore finding a temple to seek refuge in. (Episode XCIII)

After being grievously wounded and narrowly escaping from the Daughters of Aku, Jack tries to find shelter in a forest, only to turn around and notice the Omen waiting for him. Jack tries to ignore the spectre, but discovers that its mount can move. As Jack continues his search for shelter, the Omen refuses to be ignored and continues to stalk Jack while still on horseback, never taking his eyes off of him. (Episode XCIV)

Inside one of Aku's factories, the Omen seemingly claims victory as he notices Jack's grief over the unconscious kidnapped children (Who Jack believes to be dead) and speaks to him for the first time, telling Jack It is time. A broken Jack simply answers yes and follows the spirit out of the factory, leaving Ashi and the children alone. (Episode XCVI)

Some time later, Ashi finds the Omen in an ancient graveyard encouraging Jack to commit seppuku (Japanese ritual suicide) for his failure, guilt, and loss of purpose. Meanwhile, the spirits of four armored samurai emerge from nearby graves to bear witness. He attacks Ashi when she tries to stop him, but upon hearing the truth about the children, Jack intervenes and duels the Warrior. After a brief fight, Jack vanquishes him; bisecting him and causing him to disappear completely. Meanwhile, the other samurai spirits solemnly return to their graves. (Episode XCVII)

Given that he is a spirit, it is possible that he comes back into being after Jack vanquishes him. Since Jack has regain his hope, it is presumed that he ceases stalking Jack and allows him to continue his journey.

Powers and Abilities

 * Levitation: As a supernatural being, the Omen can levitate himself off the ground. He mainly does this when he does not need to ride his horse.
 * Enhanced Strength: He possesses inhuman physical strength. He is strong enough to break stone structures with one swing of his sword, lift Ashi off the ground one-handed and throw her with enough force to destroy a tombstone.
 * Master Swordsman: Because he is a patron spirit of the samurai, the Omen displays considerable skill with a sword. However, he could not hold his own against Jack when the latter had regained his will to live.

Appearances

 * Episode XCII
 * Episode XCIII
 * Episode XCIV
 * Episode XCVI
 * Episode XCVII

Quotes

 * It is time.
 * You may witness, but you cannot proceed any further.
 * The end.
 * Great warriors of past, I welcome you. This samurai has failed his purpose, and has accepted his fate.
 * This does not concern you. There is no hope.
 * Enough!
 * Hope is just a fleeting sentiment. Your failure is real. You must face the consequences, or continue to bear the guilt of your dishonor, for all eternity.
 * Death follows in your wake; men, women, children. Yes, all those children dead because of you.
 * NO MORE WORDS!

Trivia

 * The Omen might be considered the Japanese equivalent of the Grim Reaper or the Angel of Death.
 * It is possible that the Omen is really or at least based on a Shinigami - a god of death present in Japanese religion and culture. It is considered the Japanese equivalent of the Grim Reaper itself.
 * It also resembles a Nuckelavee - An Orcadian Horse/Human hybrid looking Demon that eats humans.
 * It is possible the four samurai spirits that appeared to bear witness the attempted seppuku are in fact Jack's ancestors, and the Omen is a patron spirit for those samurai warriors, as he summons them to witness the seppuku. If so, it would seem his duty is to act as an enforcer; meting judgment on samurais that have fail to uphold the bushido and their duties.
 * During his first encounter with the Daughters of Aku, Jack's hallucination once urged him to commit seppuku, claiming it was the last honorable thing they can do in what he considered a hopeless, honorless, and forsaken time. The hallucination also mentions that he is tired and that it would be a good time to end it as their ancestors were waiting and that they wished for Jack to join them before the Omen appears briefly.
 * It is unusual that the Omen (being a possible samurai version of the Reaper) pursues Jack aggressively, rather than being neutral and waiting for Jack to make his own decisions. On the other hand, it could be that he is actively motivated to seek out Jack for losing sight of his purpose and punishing him with seppuku for failing to uphold it.
 * The Omen appears to be of a slim build when he is in silhouette form, but after dismounting his horse and confronting Ashi, his true appearance is large and bulky.
 * The reason for this might be that, as he is technically a spirit, he can change his appearance to suit his needs or the situation.
 * When Jack's seppuku begins, The Omen stands behind him with his sword drawn, to act as his Kaishakunin. The role of the Kaishakunin (Or second) is to watch the disgraced Samurai, at the moment that the Samurai performs the horizontal cut across his abdomen, the second decapitates him. Aside from the purpose of being spared prolonged anguish until death, both the condemned and those on hand to observe are spared the spectacle of the writhing death throes that would ensue.
 * The Omen is symbolic of Jack's guilt and shame, driving him to punish himself when he thinks he's failed his quest.