|Born:August 13, 1859|
|October 15, 1874, for the New York Mutuals|
|Last MLB appearance|
|May 10, 1885, for the Louisville Colonels|
|Runs batted in||33|
William Henry Harrison Geer, born as George Harrison Geer, (August 13, 1859 – After 1885), was an American Major League Baseball player who played most of his career as a shortstop for five seasons and a total of seven teams. He is most notable for his status as possibly the youngest player in Major League history.
Geer made his professional baseball debut for the New York Mutuals of the National Association. The following season, while playing for the New Haven Elm Citys, he was arrested along with his roommate, Henry Luff, for burglary of several hotel rooms.
At age 15 years 63 days, he is credited as the youngest player to ever appear in a Major League Baseball game. There is controversy about his age, or the fact that the National Association has not been officially credited as a "major league". Assuming the veracity of his date of birth, he didn't actually make his Major League debut until the age of 18 years, 3 months, when he played for the Cincinnati Reds of the National League in 1878.