Kenneth Eliot "Ken" Flach (born May 24, 1963 in St. Louis, Missouri) is a former professional tennis player from the United States. A doubles specialist, he won 4 Grand Slam men's doubles titles (2 Wimbledon and 2 US Open), and 2 Grand Slam mixed doubles titles (1 Wimbledon and 1 French Open). He also won the men's doubles Gold Medal at the 1988 Olympic Games in Seoul, partnering Robert Seguso. Flach reached the World No. 1 doubles ranking in 1985.