Hard to pinpoint the genre, but Dexter is mainly a drama show with some thriller influences. But it's funny as well, but in the black/morbid way.
The show is about a police blood splatter investigator at Miamo Metro, with somewhat of a dark past. His quest in life is to remove unconvicted (but guilty) killers from society. You could say he is a serial killer with a very interesting pattern. :D
And Prison Break... that is some pathetic stuff! :D As soon as they actually broke out of that prison, the concept was stone cold dead...