Duke of Magenta (1875–1899) was one of the most successful racehorses in the United States in the 19th century.

Foaled in 1875 at the Woodburn Stud near Lexington, Kentucky, 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 Thoroughbred sire Lexington.

In 1878, Duke of Magenta won the Preakness Stakes, the Withers Stakes, the Belmont Stakes, and the Travers Stakes, a feat accomplished since by only two other colts: Man o' War and Native Dancer. Excluding the Withers, he is also one of only seven horses to have won the Preakness, Belmont, and Travers.

In Duke of Magenta's day, the Derby was a recently established race not yet considered important by East Coast breeders. Duke of Magenta died on September 20, 1899, at the farm of J. McCloud in Brookline, Massachusetts.^[1]

In 2011, Duke of Magenta was inducted into the National Museum of Racing and Hall of Fame.^[2]