What Mafia/Gang fiction books are there?

You've already been given the best answers: Mario Puzo and Lorenzo Carcaterra. By the way, Carcaterra sometimes shows up on the credits for the Law and Order series on tv as a producer or something like that. He's written several books. My mind has gone blank about who the author was (Puzo perhaps?), but don't forget the best ones--the Godfather series that were made into movies.