Extor

Extor is the creator of the Ultra-robots who appears in Episode XVIII: Jack and the Ultra-robots and Samurai Jack: The Shadow of Aku. He also made a cameo in a vision in Episode XLIII: The Aku Infection.

Background
In exchange for his his having village and it's peoples lives sparred from the wrath of Aku, Extor agree to construct for him ultimate assassins to hunt down and destroy Jack. He spent days and nights to create the Ultra-robots, designing them with nigh-destructible adamantium armor, giving each of them a unique weapon and data on Jack's fighting style, and a power source granted by Aku evil's essence. However he, like many others before, was betrayed by Aku when he ordered the Ultra-robot to destroy his village. Filled with regret for unleashing his horrible creations onto the world, Extor decided to help Jack destroy his creations. In order to aid Jack in fight the Ultra-robots, Extor gave Jack his last invention, a cybernetic, synaptically-linked dinodextric isometric poly-durataniam power gauntlet, to increase his strength to cut through the Ultra-robot armor.

After jack agreed to destroy the robots, Extor attempted to Hi five Jack, though he did not understand what a Hi five is.

During Jack's fight, Extor watched from a safe distance, cheering him as he destroyed the robot one by one, but soon grew fearful after the robot arm Jack used ran out of power, and could only watch as Jack fought against the last Ultra-robot without any aid. When Jack prayed to his great ancestors to increase the might of his sword, Extor shouted at Jack snap out it. He is then surprised when Jack's prayers are answered. After Jack destroyed the last Ultra-robot, Extor cheered with great happiness as he and rest of the world was finally rid of his creations forever before he congratulated Jack with a high five.

After past Aku's destruction, it is likely the destruction of his village by the Ultra-robots was undone since there were no Aku to order their creation. Apart from that, how it affected his existence is unknown.

Appearance
He is a medium-sized scientist that wears glasses. He also has an odd voice.

Abilities
Despite being human, Extor is a super genius, and likely one of the smartest minds on Earth in the future. His knowledge in robotics is likely superior to that of Aku's Evil Scientists', having created robots that gave Jack a real challenge. Extor is also more capable than them of making robot suited for battle, since he made the Ultra-robots study Jack's fighting skills and crafted them from adamantium, making them nigh indestructible. This shows his expertise in metallurgy as well. Extor created a cybernetic arm that enhance the wielders' strength to high levels, enough to destroy all types of metal including indestructible metals like adamantium.

Laboratory
As for the fact that he is the one who created and developed the ultimate killing machines the Ultra-robots, some parts of his work laboratory are shown.

Trivia

 * His vocal mannerisms are a reference to the title character in Jerry Lewis's The Nutty Professor.