Running an RPG with evil characters tends to be difficult. While it’s perfectly possible for players to create complex evil characters (and I’ve seen it done at my table before), they just as frequently interpret the “E” in their alignment block as a reason to maim and kill every NPC they come across.
The Pathfinder RPG is trying its hand at an evil game with the release of the Hell’s Vengeance adventure path that kicks off this month. Personally, the next time I run a game with evil PCs, I’ll probably hit my comics collection for inspiration. Specifically, the John Ostrander-written Suicide Squad title that launched in 1987 is one of the best examples of a story that made the audience cheer for the bad guys.