Blenheim (1927–1958), also known as Blenheim II, was a British Thoroughbred race horse who won The Derby in 1930. As sire, he had a major influence on pedigrees around the world. Blenheim was highly tried, by European standards, as a two-year-old in 1929, winning four of his seven races. In the following season he was beaten in his first two races before recording an upset 18/1 win in the Derby. His racing career was ended by injury soon afterwards, and he was retired to stud, where he became an extremely successful and influential breeding stallion, both in Europe and North America.

The title of champion, or leading, sire of racehorses in Great Britain and Ireland is awarded to the stallion whose offspring have won the most prize money in Britain and Ireland during the flat racing season. The current (2022) champion is Dubawi, who earned his first title after finishing runner-up multiple times.