Louis Thomas Possehl (April 12, 1926 – October 7, 1997) was an American professional baseball player. A right-handed pitcher, he played in parts of five Major League seasons for the Philadelphia Phillies (1946–48; 1951–52). He was born in Chicago, Illinois, stood 6 feet 2 inches (1.88 m) tall and weighed 180 pounds (82 kg).
Possehl appeared in 15 Major League games, eight as a starting pitcher. In 511⁄3 innings pitched, he surrendered 62 hits and 24 bases on balls, with 22 strikeouts. In his only complete game, on September 20, 1948, he defeated the Pittsburgh Pirates 7–4 at Shibe Park, allowing eight hits and four walks.