Donald Irvin Hasenmayer
- Bats Right, Throws Right
- Height 5' 10½", Weight 180 lb.
- High School Abington (PA) High School
- Debut May 2, 1945
- Final Game September 29, 1946
- Born April 4, 1927 in Roslyn, PA USA
- Died January 28, 2020 in Warrington, PA USA
Don Hasenmayer appeared in 11 major league games, with the 1945 and 1946 Philadelphia Phillies. He played second base and third base. At age 18 in 1945, he was one of the youngest players in the majors both seasons. He was the last surviving player who debuted in 1945.