Thaddeus Stanley Lepcio (born July 28, 1929, at Utica, New York) is an American former Major League Baseball utility infielder.
Lepcio attended Seton Hall University. A one-time semiprofessional baseball player in Oneida, New York, he was signed by the Boston Red Sox as an amateur free agent in 1951. He played his first Major League game in 1952 and would play most of his professional career with the Red Sox, also appearing with the Detroit Tigers, Philadelphia Phillies, Chicago White Sox and Minnesota Twins. He was generally a utility infielder who could play second and third base or shortstop. His best year was 1956, when he hit 15 home runs, nine in an eighteen-day stretch. Lepcio is mentioned in Jimmy Piersall's book, Fear Strikes Out, as his roommate during the stormy 1952 season, when Piersall had to be hospitalized with mental issues. Lepcio often saved Piersall from being beaten up by his own teammates.
On July 13, 1961 Lepcio hit a grand slam in the first inning against the Cleveland Indians, which would turn out to be the deciding factor in the Twins' 9 to 6 victory.
After he retired in 1961, Lepcio became a vice president with a New England trucking company. He also remained active in baseball and often chaired Red Sox events.