Re: The Most Heinous Star Trek Villain
-Dukat. The brilliant thing about his character was that he was given just enough humanity and awareness to make his crimes all the more wicked. He's a man who's so willingly self deluded and so obsessed with not truly examining his own sins that he actually resents the enslaved and abused people he oversees for not loving him. Someone not able to become good because he can never once question if any of his acts have been evil.
I'd like to add one other thing to your Dukat summary; toward the end, he was more like a force of chaos than any mere villain (and I mean even before he hooked up with the Pah Wraiths).
"Mu hah hah ha! And when they give me Battlestar Galactica that'll be the trifecta! My red matter and action movie scripts are unstoppable!"--JJ "Destroyer of Worlds" Abrams