Louis Mortimer Sleater (September 8, 1926 – March 25, 2013) was a left-handed Major League Baseball pitcher who played from 1950 to 1952 and from 1955 to 1958 for the St. Louis Browns, Washington Senators, Kansas City Athletics, Milwaukee Braves, Detroit Tigers and Baltimore Orioles. He stood 5 feet 10 inches (1.78 m) tall and weighed 185 pounds (84 kg). He attended the University of Maryland. He also played for 12 different minor league teams, winning 12 or more games three times in a season.