Ralph Greenleaf, American billiards player (d. 1950)
Ralph Greenleaf (November 3, 1899 in Monmouth, Illinois – March 15, 1950 in Philadelphia, Pennsylvania) was an American professional pool and carom billiards player. He was a twenty time World Pocket Billiards Champion, who dominated the sport during his heyday.

His obituary in The New York Times said of Greenleaf, in March 1950: "What Babe Ruth did for baseball, Dempsey did for fighting, Tilden did for tennis...Greenleaf did for pocket billiards."The championships of his era were contested in the game of 14.1 continuous ("straight pool"), but varied in format from contest to contest and were not annual events. Championships were challenge matches between two players often played over several days to relatively high numbers (1,500 points for example).

He was one of the first three members inducted into the Billiard Congress of America's Hall of Fame, in 1966. He was ranked number 3 on the Billiards Digest 50 Greatest Players of the Century.