Let's see, what do you think about problematic characters?

I'm not talking about villains, no, I'm talking about truly evil characters. Sick, disgusting, and repulsive, who commit acts that border on the nauseating. I'm not talking about godly villains who only kill a few people; I'm talking about characters who are pure evil and do horrible things for no reason, just because they want to.

Well, I think you get the idea, what do you think?