William Harrison "Jack" Dempsey, nicknamed Kid Blackie and The Manassa Mauler, was an American boxer who competed from 1914 to 1927, and was world heavyweight champion from 1919 to 1926. He is ranked sixth on The Ring magazine's list of all-time heavyweights and fourth among its Top 100 Greatest Punchers, while in 1950 the Associated Press voted him as the greatest fighter of the past 50 years. World heavyweight champion (NYSAC) from March 25, 1920 to July 2, 1921. Wiki link