Otto Charles Deininger
- Bats Left, Throws Left
- Height 5' 8½", Weight 180 lb.
- Debut April 26, 1902
- Final Game October 7, 1909
- Born October 10, 1877 in Wasseralfingen, Germany
- Died September 25, 1950 in Boston, MA USA
He was with the Toledo Mud Hens in 1904, then played for the Altoona Mountaineers from 1906 to 1908, after playing a single game as an outfielder with the Philadelphia Phillies at the start of the year. The Phillies had originally purchased his contract in 1907, but he had not been allowed to play for them because he was considered a "contract-jumper"; the ban was lifted after he paid a $300 fine to the National Association after the 1907 season. Deininger had most of his major league at-bats with the Phillies in 1909, hitting .260 on a team that hit .244 (in a league that also hit .244). In 1910, he led the Eastern League in RBI while playing for the Jersey City Skeeters, with whom he also played in 1911.
He was on the Board of Directors of the Baseball Players Fraternity in 1914, with his location listed as Montreal, QC. Ty Cobb, Max Carey, Sam Crawford and Fred Merkle, among others, were also on the board.