Bold Ruler (April 6, 1954 – July 11, 1971) was an American Thoroughbred Hall of Fame racehorse who was the 1957 Horse of the Year. This following a three-year-old campaign that included wins in the Preakness Stakes and Trenton Handicap, in which he defeated fellow Hall of Fame inductees Round Table and Gallant Man. Bold Ruler was named American Champion Sprinter at age four, and upon retirement became the leading sire in North America eight times between 1963 and 1973, the most of any sire in the twentieth century.