Daniel J. "Danny" O'Leary (January 30, 1900 - August 15, 1928) was an Irish Philadelphia mobster involved in bootlegging who, a rival of Maxie "Boo Boo" Hoff throughout Prohibition, would struggle for dominance among the many gangs of Philadelphia's underworld.[citation needed] His death, only six days after his participation in the gangland slaying of Hugh "Hughie" McLoon, would mark the beginning of gang wars during the late 1920s eventually leading to a Special August Grand Jury investigating corruption and influence of organized crime in the city.[1][additional citation(s) needed]