Dark Secret (1929 – September 15, 1934) was an American Thoroughbred racehorse. He was bred and raced by Wheatley Stable, a partnership between Gladys Mills Phipps and her brother, Ogden Mills, the United States Secretary of the Treasury. Dark Secret was the son of 1925 Kentucky Derby winner Flying Ebony. His dam was Silencia, a daughter of King James who was the American Champion Older Male Horse of 1909.