I got the idea for this thread on my way to work today, they were talking about Hannibal Lecter on NPR, and I realized what a likeable character he is, especially for a crazed villian. So that leads to the question, who is your favourite villian; not because of how evil they are, but how strangely likeable they are. This can transcend movies, video games, etc.
I agree with DragonMistress that Hannibal is a very lovable character. He is such a gentleman, one who will kill you but apologize for it. I also like the Joker, because who could deny that he's awesome and has, as Goumas said, a great sense of humor (no matter how gruesome it is). Another one of my all-time favorites is Doc Oc, the mechanical arms are awesome and how could you not love him after the way he goes out?
As Badass as i think the Joker is, i'd have to say my favorite enemy is either Carnage or the Iron Patriot. Daken (Wolverine's son) is pretty awsome too.
I am quite partial to Hannibal Lecter. He strikes me as a villain I would enjoy being in the company of. Another would have to be Magneto from X-Men. Sure, he's the bad guy, but he really has the same agenda as the good guys, he's just taking the devil's advocate approach. He is also very calculating and intelligent, and there is great depth to his history and motives.