Aggregor

Agreggor(voiced by John DiMaggio) is a villain in the new series Ben 10: Ultimate Alien. In Ultimate Crisis (Cartoon Network Official Game), Agreggor has robot drones. Agreggor also kidnapped the 5 new aliens in Ultimate Alien from the Andromeda Galaxy so it is possible he came from there as well.

He appears in the first episode of Ultimate Alien, Fame, where he shows up at the end and presumingly kills one of the aliens he kidnapped Bivalvan. He may have magical powers like a wizard

Appearance
Agreggor has long black hair and pale pink skin along with small horns coming out of his head. He is an Osmosian (like Kevin) and plans to absorb the powers of five aliens and make himself unstoppable. Adult Osmosians grow antlers as they mature (confirmed by Dwayne McDuffie)

Trivia

 * Agreggor's appearance is very similar to a Zabrak (more pacifically Eeth Koth) from Star Wars. It is possible Agreggor is based off a Zabrak.
 * His appearance is also similar to some depictions of the devil (specifically the horns and pitchfork).