Oscar Horstmann debuted on April 18, 1917, playing for the St. Louis Cardinals at Robison Field; he played his final game on June 1, 1919, playing for the St. Louis Cardinals at Robison Field.
Oscar Azocar debuted on July 17, 1990 and played his final game on October 4, 1992.
Oscar Bielaski debuted on April 24, 1872 and played his final game on July 21, 1876.
Oscar Brown debuted on September 3, 1969 and played his final game on September 30, 1973.
Oscar Dugey debuted on September 13, 1913 and played his final game on August 15, 1920.
Oscar Estrada debuted on April 21, 1929 and played his final game on April 21, 1929.
NFL player Oscar Johnson played for Louisiana Tech.
Oscar Dugey debuted on September 13, 1913, playing for the Boston Braves at South End Grounds III; he played his final game on August 15, 1920, playing for the at .
Oscar Henriquez debuted on September 7, 1997, playing for the Houston Astros at Astrodome; he played his final game on September 8, 2002, playing for the Detroit Tigers at Comerica Park.
Oscar Zamora debuted on June 18, 1974, playing for the Chicago Cubs at Wrigley Field; he played his final game on July 21, 1978, playing for the Houston Astros at Astrodome.
Oscar Purner debuted on September 2, 1895, playing for the Washington Senators at Boundary Field; he played his final game on September 2, 1895, playing for the Washington Senators at Boundary Field.
Oscar Siemer debuted on May 20, 1925, playing for the Boston Braves at Braves Field; he played his final game on September 18, 1926, playing for the Boston Braves at Braves Field.
Oscar Stanage debuted on May 19, 1906, playing for the Cincinnati Reds at Palace of the Fans; he played his final game on June 17, 1925, playing for the Detroit Tigers at Navin Field.