St. Gatien (1881–after 1906) was a British Thoroughbred racehorse and sire. In 1884 he was involved in the second and final dead heat in the history of The Derby, part of an unbeaten sequence of twelve races. St. Gatien went on to become a dominant performer in long-distance races, winning the Gold Cup and the Alexandra Plate at Royal Ascot, the Cesarewitch Handicap carrying a record weight, and three successive running of the Jockey Club Cup.