Lou Klein, American baseball player, coach, and manager (d. 1976)
Louis Frank Klein (October 22, 1918 – June 20, 1976) was an American professional baseball player, manager, coach and scout. During his active career he was an infielder in the Major Leagues for the St. Louis Cardinals, Cleveland Indians and Philadelphia Athletics, and was known as one of the players who "jumped" to the Mexican League in 1946. He was then suspended by Commissioner of Baseball Happy Chandler for a five-year span, although the suspension was later reduced.

Born in New Orleans, Klein attended Peters High School in that city. As a player, he was listed as 5 feet 11 inches (1.80 m) tall and 167 pounds (76 kg) and threw and batted right-handed.