Boldboy (1970 – September 1998) was an Irish-bred, British-trained Thoroughbred racehorse. He raced for eight seasons in the 1970s and was one of the most popular and successful racehorses of his era. As a two-year-old he showed ability, but his ungovernable temperament led to his being gelded. In the following year he won the Greenham Stakes, Prix de la Porte Maillot, Diadem Stakes and Challenge Stakes.