Ballymoss (1954–1979) was an Irish Thoroughbred racehorse. In a racing career that lasted from 1956 until November 1958, he ran seventeen times and won eight races. In 1957, he became the first horse trained in Ireland to win the St Leger. The following season, he was Europe's leading middle-distance horse, winning the King George VI and Queen Elizabeth Stakes and the Prix de l'Arc de Triomphe.