Time Between Dog and Wolf - This drama screams revenge from beginning to end. Memory loss, federal agent to gangster... he's not really evil though. Kinda soft, but it's Lee Jun Ki so- If you decide to watch, hang in there until he actually loses the memories.
Cain and Abel - Memory loss, temporarily turns from doctor to drug-dealer sand gangster.
Byakuyako (the drama) - After this one scene (ep.3 I believe), pretty sure that he is classified as evil. Misunderstood and/or screwed up because of a girl evil maybe. Both of them are disgusting excuses as people, no matter how they got there - it's the final product that counts.
Rough Cut - Not good, not bad. The ending will have you decide.
Psychic - Misunderstood guy with a pretty shitty childhood that also happens to bear supernatural powers is a main. He's a "bad guy" I guess
I'm A Killer isn't released yet, but it seems interesting.