Charles Dean O'Banion was an American mobster who was the main rival of Johnny Torrio and Al Capone during the brutal Chicago bootlegging wars of the 1920s. The newspapers of his day made him better known as Dion O'Banion, although he never went by that first name. He led the North Side Gang until 1924, when he was shot and killed, reportedly by Frankie Yale, John Scalise and Albert Anselmi.

John Donato Torrio was an Italian-born American mobster who helped build the Chicago Outfit in the 1920s later inherited by his protégé Al Capone. Torrio proposed a National Crime Syndicate in the 1930s and later became an adviser to Lucky Luciano and his Luciano crime family.