Clarence Joseph Kummer (August 8, 1899 – December 18, 1930) was a U.S. Racing Hall of Fame jockey who won four American Classic Races. In early 1920, Kummer rode the 1919 Triple Crown Champion Sir Barton to a new Saratoga track record in winning the Saratoga Handicap. In May 1920 he was given the opportunity to ride Man o' War. He rode the horse to nine wins in nine starts. Kummer's successes in 1920 made him that year's top money-winning jockey in the United States. Clarence Kummer was inducted in the United States' Racing Hall of Fame in 1972.