John Thaddeus Ostrowski (October 17, 1917 – November 13, 1992) was an American professional baseball player. Born in Chicago, he was an outfielder and third baseman who spent all or part of seven Major League seasons (1943–1946; 1948–1950) with the Chicago Cubs, Boston Red Sox, Chicago White Sox and Washington Senators. Listed at 5 ft tall and 170 lb, Ostrowski batted and threw right-handed. Over his 216 MLB games played, Ostrowski was a .234 hitter (131-for-561) with 14 home runs and 74 RBI in 216 games, including 73 runs, 20 doubles, nine triples, seven stolen bases, and a .321 on-base percentage. However, in a 1,600-game minor league baseball career, Ostrowski hit 218 home runs and five times exceeded the 20-homer mark, including two 30 home run seasons. Ostrowski died in Chicago at the age of 75.