Magneto-- [Timeless anti-hero. A man to be both respected and feared]
Grodd-- [Crazy psychopath monkey. Torn between the JLU intelligent version and the crazy flesh eating comics version, who seems to have rabies]
Apocalypse-- [Unstoppable mutant who has planned his ascension since the days of ancient Egypt. From the virus he infected Cable with at birth, to his relationship with Mr. Sinister, to the Age of Apocalypse]
Thanos-- [Wondering nomad plotting the end of reality itself. Practically unstoppable, and played the anti-hero part in Marvel: The End and his own series quite well]
Doom-- [Doom is a force of nature. He rules his own country with an iron fist, and his ascension by trading in his ex-lover was beautiful]
Kang-- [No real reason, he's just a constant thron in the Avengers' side and I find him amusing.]
Ra's-- [Batmans deadliest foe. Ra's is one of the best villains ever concieved, and his motives are very sound indeed]
Kingpin-- [90's cartoon, his control over NY, and even his fall from grace in Bendis' Daredevil run]