Doc Satan is one of the most prominent super-villains in the Millennium Comics universe.
Ganzar Prime is an alien world that orbits a distant star. On the verge of a terrible war, a colony ship was dispatched by one of the sides in hopes that someone could survive what they feared would be a planet-killing disaster. But unfortunately, the ship was sabotaged. As it approached the target planet--Earth--its systems failed. Most of crew were killed. A robot managed to get one baby into a life support pod before the ship broke up in the atmosphere. By a one-in-a-million chance, the robot partially survived the crash. Its head and some debris were found by a ex-cop engineer name Harry Dale who managed to get the head working again. The head was able to tell him how to repair the rest of him, earning from Harry the nickname "Mentor."
Thus Mentor awoke on a strange alien world, his home forever lost. His friend Harry suggested he use his abilities to fight evil, which struck him as a very worthwhile idea. So that is what he did.
Doc Satan was the baby saved by Mentor when the Ganzarian ship crashed. Because it was years before Mentor's robotic head was found and still more for Harry Dale to repair him, that child was found and reared by a poor Irish couple who later moved to Millennium City. Mentor eventually tracked down the baby to tell him his origin, discovering a brilliant student who was about to get a doctorate (on both academic and athletic scholarships) at age eighteen! But Carl Kennedy (as he was called) was also a disturbed youth, convinced of his own superiority while harboring deep resentments of those in better social strata than himself. He also had a terrible temper. Upon learning he wasn't even human, and that he could expect to live several more centuries (Ganzarians live to be 300 thereabouts), Carl reacted with glee and paranoia. Certain he was in fact better than mere humans, he was also certain they would never accept him. His only choice if he wanted to survive, was to conquer the planet. So "Doc Satan" was born, one of the most dangerous supervillains ever known--and one with a particular fear/hatred of Mentor.
Doc Satan kidnapped his former sometime collaborator Vixen and the submarine genius Stingray in order to make evil doppelgangers of them who would commit crimes and ruin their reputations. The heroes, however, got the better of Doc Satan and trapped him in his own (presumably wrecked) device. Although they thought they had seen the last of him, a deformed Doc Satan was soon spotted outside the borders of Millenium City. The heroes and police gave chase. Doc Satan fled into the twisting corridors Monday Slough outside Millenium City after incapacitating Vixen. Stingray, however, used his atomic submarine suit to infiltrate Doc Satan's defenses. Once Stingray had cornered Doc Satan, he realized the truth. The chalk-skinned, green-haired brute was not Doc Satan at all!
The creature, who called himself Doc Gabriel, explained that Doc Satan's machine, which had been intended to make perfect evil duplicates of the human heroes, had instead created an good duplicate of the alien humanoid Doc Satan, whom Doc Gabriel had left still trapped in the duplication machine. Doc Gabriel explained that the duplication ray designed for human duplication did not work perfectly for Doc Satan's species. Despite his astonishment at this tale, Stingray offered to put in a good word for his fellow genius inventor. Doc Gabriel refused because he felt he could counter Doc Satan's future schemes as a hidden force.