Fair Play (April 1, 1905 – December 17, 1929) was an American-bred Thoroughbred racehorse who was successful on the track, but even more so when retired to stud. He is best known as the sire of Man o' War, widely considered one of the greatest American racehorses of all time. On the racetrack, Fair Play was known for his rivalry with the undefeated Colin, to whom he finished second in the Belmont Stakes. Later, Fair Play was the leading sire in North America of 1920, 1924 and 1927, and the leading broodmare sire of 1931, 1934 and 1938. He was inducted into the National Museum of Racing and Hall of Fame in 1956.