Kenneth Eliot Flach (May 24, 1963 – March 12, 2018) was an American doubles world No. 1 tennis player. He won four Grand Slam men's doubles titles (two Wimbledon and two US Open), and two mixed doubles titles (Wimbledon and the French Open). He also won the men's doubles gold medal at the 1988 Seoul Olympics, partnering Robert Seguso. Flach reached the world No. 1 doubles ranking in 1985.