Al Capone is the most famous one, and a lot of them are notorious (most recent, of course, Teflon Don Gotti), but the way Charlie Lucania aka "Lucky" Luciano set up the two biggest crime bosses of the late 20's (enemies) and killed them both to become the great emperor himself, is enough for me to be called the #1 mafia king ever, if such a title would be appropiate. No matter how influential Gambino and Bonnano and others were...

Too bad the movies about Luciano aren't that special (the Christian Slater picture is awful).