Frank Joseph "Lefty" Hoerst (August 11, 1917 – February 18, 2000) was an American Major League Baseball pitcher.

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.

He then spent most of the 1947 season back in the minors with the Memphis Chickasaws, pitching in just four major league games.

Hoerst died on February 18, 2000, and was interred at Holy Sepulchre Cemetery in Cheltenham Township, Pennsylvania.