Quote Originally Posted by Azar
While this isn't technically a video game character, he's been IN some games. Darth Vader, man. He's the personification of evil, but the depth of his character and his eventual return to the light side makes him one of the best villians of all time. I can't think of anyone better at the moment, anyway.
I always found Ernie McKraken(sp?), from Kingpin, to be the greatest movie villain of all time. At least, the most evil, detestable character ever invented.

As for video games... I've never gone beyond limited SNES RPGs, but I think that Kefka is a pretty bad dude.