| Oscar Siemer | |
| Position: | Catcher |
| Birth Date: | August 14, 1901 |
| Birth Place: | St. Louis, Missouri |
| Death Place: | St. Louis, Missouri |
| Bats: | Right |
| Throws: | Right |
| Debutleague: | MLB |
| Debutdate: | May 20 |
| Debutyear: | 1925 |
| Debutteam: | Boston Braves |
| Finalleague: | MLB |
| Finaldate: | September 18 |
| Finalyear: | 1926 |
| Finalteam: | Boston Braves |
| Statleague: | MLB |
| Stat1label: | Batting average |
| Stat1value: | .244 |
| Stat2label: | Home runs |
| Stat2value: | 1 |
| Stat3label: | Runs batted in |
| Stat3value: | 11 |
| Teams: |
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Oscar Sylvester "Cotton" Siemer (August 14, 1901 - December 5, 1959) was a Major League Baseball player. He played two seasons with the Boston Braves from 1925 to 1926.[1]