Louis Mortimer Sleater (September 8, 1926 – March 25, 2013) was an American 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.

A knuckleball specialist, Sleater was signed as an amateur free agent by the Boston Braves in 1946.

Sleater made his big league debut with the Browns on April 25, 1950, at the age of 23.

In his first game, he pitched one inning, striking out a batter and allowing no hits, no walks, and no runs.

On May 30 of that year, he hit a game ending home run, to become one of ten pitchers to accomplish that feat since the 1957 season.

He started the year with the Tigers, but after posting a 6.75 ERA in four games with them he was purchased by the Orioles on June 2.

He played his final major league game on September 28, and was released by the Orioles on October 16, 1959.

Sleater played for a total of six major league teams in his seven-year career.

[6] During spring training for the Browns one year, Ned Garver had pitched eight hitless innings against the Cardinals in Houston.

His manager asked him if he wanted to pitch the ninth to complete the no hitter, but Garver declined, as he was more concerned with conditioning himself for the regular season.