Hey /r/Batman, who is your favorite Batman villain that's not the Joker?

Pretty much anyone who answers Joker! :D is pretty much basing it off the movies, Animated Series. Joker is a great and loveable character, but honestly sometimes you can tell how much someone knows by picking the most predictable character. It's like when people say "Harley Quinn should be in the next movie!" when a true bat fan knows it's in a completely different universe. There's many, many great villains to choose from ,and it doesn't have to be in his universe, there has been many crossovers from other DC Heroes villain vault. So Reddit, who is your favorite villain? Power doesn't make a great character, it can help ,but who do you find fun to read/watch?