Lucky Luciano, Monk Eastman, Al Capone, John Morrissey?
My vote is with Morrissey. He was a street gang leader (dead rabbits), bare-kuckle boxing champ (beat Yankee Sullivan), and street brawler (fought along the docks for money when younger.)
Eastman, no slouch himself, runs a close second. He was a madman who went through actual war (WWI) as well as being a notorious pugilist and gang leader.
