James John Corbett was an American professional boxer and a World Heavyweight Champion, best known as the only man who ever defeated John L. Sullivan. Despite a career spanning only 20 bouts, Corbett faced the best competition his era had to offer, squaring off with a total of nine fighters who would later be enshrined alongside him in the International Boxing Hall of Fame. World heavyweight champion (World) from September 7, 1892 to March 17, 1897. Wiki link