I would have to put Hannibal Lecter. Deceptively smart and unnaturally cunning as well as horribly depraved. There's a certain element of sorrow in his back story that almost makes his actions as a murder and cannibal justified.
Jason Vorhees. I've always liked the irony that such a deranged, merciless psycopath is also the ultimate mama's boy.
"Oh, you think darkness is your ally. But you merely adopted the dark; I was born in it, moulded by it. I didn't see the light until I was already a man, by then it was nothing to me but BLINDING!"
If we're just counting movies, my favorite Villain is Doctor Horrible, though, he's technically the protagonist, he's still the villain. NPH is my waifu If we're counting more than just movies, because I personally prefer video game villains to movie villains, then I would say that my favorite would be Gwyn, The Lord of Cinder from Dark Souls. I just love the way that he's only the villain because he's not ready to relinquish his role as the hero of the world, and so you're forced to kill him and take his place. Spoiler: Large Image
"you see, in their last moments, people show you who they really are. So in a way, I know your friends better than you ever did......" "Would you like to know which of them were cowards?"
I'm very passionate about film, especially movies in which there is a powerful, challenging villain, so my list is practically endless. But if I were to go with pure, bone-chilling terror, I'd definitely have to go with Anton Chigurh from the Coen Brothers' masterpiece No Country for Old Men. "You know how this is gonna to turn out, don't you?" "Nope." "I think you do. So this is what I'll offer: you bring me the money, and I'll let her go. Otherwise she is accountable. Same as you. That's the best deal you're gonna get. I won't tell you you can save yourself, because you can't."
Hans Landa from Inglorious Basterds. The fact the he can be so affable and friendly at the same time he's being so unrepentently evil is just chilling especially in the first part of the film. Cristophe Waltz truly earned the Oscar he got for that role.
That was my 2nd choice, and I was actually pretty conflicted choosing between the two (and it's great that they both won Oscars for their roles). The first few minutes of that movie and how nonchalant he is as he's literally hunting human being is still chilling.