There have been 13 Triple Crown winners in U.S. Thoroughbred horse racing.

What “Triple Crown winners” means

In U.S. horse racing, “Triple Crown winners” usually refers to horses that won all three races in the American Triple Crown: the Kentucky Derby, the Preakness Stakes, and the Belmont Stakes in the same year.

The 13 Triple Crown winners (USA)

The 13 winners are: Sir Barton (1919), Gallant Fox (1930), Omaha (1935), War Admiral (1937), Whirlaway (1941), Count Fleet (1943), Assault (1946), Citation (1948), Secretariat (1973), Seattle Slew (1977), Affirmed (1978), American Pharoah (2015), and Justify (2018).

If you meant Triple Crowns in another country (like the British or other national Triple Crowns), the number of winners is different, and there are multiple Triple Crown series worldwide.