eninac.

Are you saying the computer is God? Wait, that was ENIAC.

Whew, for a moment I thought someone was going to tell me that Charles Babbage was secretly Jack the Ripper.

Not the computer. The neighbor's dog.

Red Skull - a weakling and a coward who is shaped by Hitler into becoming the Ubermensch. The Nazi Captain America before there was a Captain America. There is an issue from Cap vol III that is a great recount of Skull's back story. Everything in his life is monochrome black and white except the Skull until he meets and fights Captain America (even the girl he thinks he loves at one point stays black and white) who gradually takes on a non-monochrome appearance.

Loki - Has a lot of daddy related issues. Basically begins acting out through a need to recieve his father's approval and to diminish his father's favorite son. Which ultimately leads him down darker and more twisted paths. At the end of the day he wants the adulation and attention Thor gets.

Poison Ivy is fascinating when written properly. At any time she could just walk away from the human world and set up her own personal kingdom in the middle of a rainforest, but she just can't deny the human animal aspect of herself that desires to stay involved in the everyday pettiness of modern life.

A bit like Dr. Manhattan, but lower in magnitude. You wonder why she's even bothering to interract with others on their level until you realise that despite the ridiculously godlike power and lack of any true attachment to society she's mentally unable to burn the bridges to her animal instincts. Whereas Manhattan is taken outside the human condition and so gradually drifts off into a perspective of his own, Ivy is handed a completely different "plant condition" (taking her far further from humanity than say Grodd, Magneto or even Ultron are) which puts her at odds with as well as outside of human conventions.

I've always thought locking her up in Arkham was completely preposterous and showed how normal society literally has no idea how to comprehend her, but in a way an occasional spell locked up is one of the few things that keeps her grounded.

Joephisto.

What about Red Hood?

Batman has some great villains as mentioned above(Two Face, Bane, Joker, Ra's al-Ghul, etc.).

Personally, I would add Sinestro in, since he was a good guy gone bad. And he's my favorites character lol.

Green Goblin is a pretty cool villain also.

Which one??? They were/are all nutty.