Aggregor

Aggregor (voiced by John DiMaggio) is a villain in the new series, Ben 10: Ultimate Alien, an Osmosian (same species as Ben's former nemesis current best friend Kevin) warlord with lethal absorbing powers. He was introduced in Fame (though his nature was only truly explained in Escape From Aggregor), and serves as the main antagonist of the series. His objective is to absorb the powers of various powerful aliens he captured from the Andromeda Galaxy in order to become strong enough to gain what he calls the "ultimate prize" which could be none other than the Ultimatrix that is currently in Ben's possession.

Appearance
Aggregor's appearance is, for the most part, similar to that of a human. However, he has pink, pale skin and small horns coming out of his head. He has long black hair and red eyes. He wears a brown tunic and wields a spear-like weapon. In episode Escape From Aggregor, his species is confirmed to be Osmosian.

Powers and Abilities
Being an Osmosian, Aggregor has the abilities to absorb energy. While Kevin now relies more on his matter absorbing powers, Aggregor fully masters his powers, and prefers absorbing energy from aliens, acquiring for a limited amont of time their power with 1/10 of its strengh. Unlike Kevin, who, even as a villain, let the alien he absorbed powers from unharmed, Aggregor absorbs all their energy, including their life force, letting nothing else from them than an horrific skeleton-like dead body.

In addition to his powers, Aggregor is a skilled hand-to-hand fighter, and relies on a spear-like weapon who can be used to stab enemies, as well as shooting red lightning-like energy. Much like Ben's archennemy Vilgax, he uses robot drones as his army rather than living soldiers.

Ultimate Alien
In Fame, after Bivalvan was defeated by Ultimate Spidermonkey, he explains that Aggregor captured him and his four other aliens but he managed to escape to Earth. At the end of the episode, instead of the Plumbers who Bivalvan was expecting to send him back to his planet, Aggregor appeared, having found him somehow. His first line was "No one escapes me, Bivalvan". Bivalvan is then heard screaming offscreen, indicating that Aggregor either killed him or tortured him before taking him away.

He appeared again in Escape From Aggregor, where Galapagus told the tale of how he and the other aliens were captured and escaped. Aggregor revealed that his plan was to absorb the full power of the five aliens he captured, making himself invincible so he can obtain the ultimate prize. At the end of the episode when Ben and the others sent Galapagus back to his world, the Plumber agent that was transporting him is revealed to be actually Aggregor in disguise. As Aggregor has said that he must use his machine on his homeworld in order to absorb all the powers of the five aliens, it's possible that Bivalvan and Galapagus are still alive at least until Aggregor captures the remaining three.

Trivia

 * Aggregor's appearance is very similar to a Zabrak (more specifically Eeth Koth) from Star Wars. It is possible Aggregor's appearance is based-on a Zabrak.
 * His appearance is also similar to some depictions of the devil (specifically the horns and pitchfork-like staff).
 * According to Dwayne McDuffie, he is a much greater threat than Vilgax.
 * He appears to be over a century old, due to the antlers he's grown.
 * It is interesting to note that the five aliens he kidnapped have powers based on the five elements (Water, Wind, Fire, Earth, and Electricity) which may have something to do with him wanting their powers.


 * His sinister and mysterious personality is similar to the Sam Neill character of the possessed Dr. William Weir from Event Horizon.