Duke of Magenta was one of the most successful racehorses in the United States in the 19th century.

Born in 1875, he was owned by New York City tobacco tycoon, George L. Lorillard and trained by Hall of Famer R. Wyndham Walden. "Duke of Magenta" was one of the last sons of the legendary thoroughbred sire Lexington. In 1878, he won the Preakness Stakes, the Withers Stakes, the Belmont Stakes, and the Travers Stakes, a feat accomplished since by only two other colts, both legends of the sport: Man o' War and Native Dancer. Even the trio of Preakness, Belmont, and Travers have only been won by six horses, compared to the eleven who have won the modern Triple Crown of Preakness, Belmont, and Kentucky Derby.

In Duke of Magenta's day, the Derby was a recently established race not yet considered important by East Coast breeders.