So that's what happened to Mitch Hedberg I did not know that, thanks for the creation of this thread, I had no idea he would be so well known. Besides him and the other classic greats that have already been mentioned I would say Lewis Black and Mitch are 2 of my favorite and if I watch them long enough I find myself talking like them for a few days.
Oh and on actor/entertainer that is no longer thought of as a comedian that I liked way back in the 80's is Howie Mandel. When I first saw him it was on a showtime/hbo way before he had the cartoon Bobbie but used the voice in his stand-up, had long curly hair and wasn't a germaphobe also if I remember correctly one of his Showtime or HBO specials had a very young Jeff Dunham when he only had 3 puppets of Peanut, Walter and Jalapeno-On a Stick when he was actually funny.