To be honest, I'm really sick of "evil" characters.
Evil is not a personality trait. Just as no one can be perfectly good, no one is purely evil since it's pretty much a matter of moral opinion. People's ideas of what's bad and what's not vary, so what's evil to one might be perfectly acceptable to another.
Just saying they're evil doesn't tell you much of anything. Maybe they're a raging psychopath, or maybe they're just misguided, or perhaps they want revenge. Point is, they're not just being mean for the heck of it, and they're such as heck not going to believe they're the bad guy. For the most part, they probably think they're doing the right thing. (Or they know it's wrong, but then they wouldn't be purely evil since they at least know enough to know it's wrong, right?)
There's all kind of ways to make your characters sick and twisted maniacs, or in any other way a villian, but just using "they're evil" as a justification for their actions is just lazy. There's far more to people than just being good or bad, they're usually somewhere in between.