Favorite Character Actor in a Lead Role?

What's your favorite time a charactor actor or actress has played a leading role? I'm struggling to think of many; there are several people that have started as character actors and eventually starred in several films (e.g Jonah Hill). One that comes to mind is Allen Covert in Grandma's Boy. He has and still does play minor and supporting roles, but he got a random lead role. via /r/movies http://ift.tt/2uoPtWh