Frank Joseph "Lefty" Hoerst (August 11, 1917 – February 18, 2000) was a Major League Baseball pitcher. He pitched all or part of five seasons for the Philadelphia Phillies. He made his MLB debut in 1940, pitching in six games with the Phillies while spending most of the season with the minor league Pensacola Pilots. Hoerst played the entire 1941 and 1942 seasons in the majors before serving with the Navy during World War II. Hoerst returned to pitch for the Phillies in 1946. He then spent most of the 1947 season back in the minors with the Memphis Chickasaws, pitching in just four major league games. After spending all of 1948 with Memphis, Hoerst's professional career was over.