Western comic books? I'd have to say the Joker, he's one of the most infamous and classical villains for good reason. He's crazy enough to do anything. Also Heath Ledger's interpretation of him was pretty haunting. Pretty keen to see how the Suicide Squad version of him will fare.
Man Comic Book wise there are too many to pick just one but ultimately I would have to say Bane and Doomsday. Just because they get the credit for taking out two of the top well known superheros in the world. So anything with those names in it makes it must see for me so you could only imagine my disappointment with the Batman v Superman movie. I mean, as if DC didn't mess up that character enough they go and let Zack what ever his name make a ninja turtle Doomsday.
Man Comic Book wise there are too many to pick just one but ultimately I would have to say Bane and Doomsday. Just because they get the credit for taking out two of the top well known superheros in the world.
I'm not really into western comic books, so I can't really answer you. But when it comes to anime, I truly enjoyed Grell Sutcliff from Kuroshitsuji, I'm not really sure if he can be considered as a supervision (since he was actually, one of the worst violence, not in a good way) but he was hilarious and kind of dark and cold at the same time. I can say a pretty similar thing when it comes to Alois Trancy, but I kind of hated him at the end of the anime.
Super villain doesn't have to be evil right? If that is the case, then ulquiorra. I really didn't want Ichigo to win that fight. It was really sad to watch those episodes. I couldn't bring myself to re watch them again