Something I hit up yesterday.
Now, for playable evil:
-Selfish. By the definition of evil in the book, you are a mild sort of evil simply by being willing to profit at the expense of others. Lots of plain old mercenaries, footpads and merchants fall into this fairly easily, if they're willing to hire out to do dirty jobs. This is the easiest form of evil for most parties to indulge in, after all its practically identical to most adventurers manifesto, especially the looting and killing.
-Evil Goals. Perhaps they are a nice person, who does charity and whatnot, but they have ultimately inimical goals that will involve a lot of people in a lot worse times. Maybe they are the affably evil priest of Asmodeus who plans to subvert the government structure and setup things for a destructive war. Maybe they worship aberrations from Beyond, and wish to open the Outer Gates for the 'good' of all. Very safe in terms of comfort zones, you're going to end the world but theres no sense being a bitch about it. Sometimes its the boss who requires regular questionable acts like weekly sacrifices.
-Evil Means. Their goals might be noble, but they've gone and jumped off the slippery slope in seeking it. Save a child, damn the world. Torture people for information, etc. This is also one of the easiest for adventurers to slip into, as well as Dark Knight sorts. This is also the easiest to cross comfort zones, especially with torture, kidnapping and murder, but likely not rape.
-Evil Inside(TM). Maybe they're just that sick. This is for sick and depraved individuals, they like to kill, they enjoy rape, they would turn people into frogs for shits and giggles. BUT, they have to get away with it. They are sick and twisted, not insane or stupid. No stabbing the captain of the guard just because, but maybe, just maybe, ambush people at night and drag them off for bloody murder. Probably what most of the failures are trying for, but failing. Very easily screwed up. This is the refined form of Killfucksoulshitter.