Louis Straight Clark (February 10, 1925 – February 10, 1995) was an American tennis player in the mid-20th Century. He was born in Des Moines, Iowa.
A member of the U.S. Davis Cup team, he was 5–0 in matches in 1953 and 1954.
In 1954, he won the singles title at the tournament in Cincinnati, defeating Sammy Giammalva, Sr., 8–6, 6–1, 6–1 in the final.
He reached the final at the Newport Casino Invitational in 1954, only to lose to Hamilton Richardson 6–3, 9–7, 12–14, 6–8, 10–8, in a match that lasted more than four hours.
In 1951, he knocked off Whitney Reed to reach the final of the Pennsylvania State tennis championship, only to fall to future Hall of Famer Vic Seixas.
When he teamed with fellow American Hal Burrows, the pair became one of the top doubles teams of their time. They reached the finals of the U.S. Clay Court Championship, and the semifinals of the U.S. Nationals, upsetting the team of future International Hall of Famers Ken Rosewall and Lew Hoad in the quarterfinals. Clark and Burrows also reached the quarterfinals at the French National Championships, Rome and Wimbledon.