John Leonard Hopp (July 18, 1916 – June 1, 2003) was an American professional baseball player and coach. Born in Hastings, Nebraska, he was an outfielder and first baseman who appeared in 1,393 Major League Baseball games over 14 seasons (1939–52) for the St. Louis Cardinals, Boston Braves, Pittsburgh Pirates, Brooklyn Dodgers, New York Yankees and Detroit Tigers. He threw and batted left-handed, and was listed as 5 feet 10 inches (1.78 m) tall and 170 pounds (77 kg). He was nicknamed "Cotney" as a youth because of his blond ("cotton-top") hair.