Giovanni Ignazio Dioguardi (April 29, 1914 – January 12, 1979), also known as John Dioguardi and Johnny Dio, was an Italian-American organized crime figure and a labor racketeer. He is known for being involved in the acid attack which led to the blinding of newspaper columnist Victor Riesel, and for his role in creating fake labor union locals to help Jimmy Hoffa become General President of the Teamsters.