Gregory Duncan "Don" Cameron (c.1894 - July 11, 1952) was an American Thoroughbred horse trainer who won the U.S. Triple Crown in 1943.A native of California, Don Cameron served as an aviator in the United States Military during World War I. Working in the Thoroughbred horse racing industry, he trained for various owners including the prominent stables of Vera S. Bragg and J. Shirley Riley.