| Johnny Ostrowski | |
| Position: | Left fielder / Third baseman |
| Bats: | Right |
| Throws: | Right |
| Birth Date: | 17 October 1917 |
| Birth Place: | Chicago, Illinois, U.S. |
| Death Place: | Chicago, Illinois, U.S. |
| Debutleague: | MLB |
| Debutdate: | September 24 |
| Debutyear: | 1943 |
| Debutteam: | Chicago Cubs |
| Finalleague: | MLB |
| Finaldate: | October 1 |
| Finalyear: | 1950 |
| Finalteam: | Chicago White Sox |
| Statleague: | MLB |
| Stat1label: | Batting average |
| Stat1value: | .234 |
| Stat2label: | Home runs |
| Stat2value: | 14 |
| Stat3label: | Runs batted in |
| Stat3value: | 74 |
| Teams: |
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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 5inchesftNaNinchesin (ftin) tall and, 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.