|Country (sports)||United States|
November 1, 1907|
Newark, New Jersey
|Plays||Right-handed (one-handed backhand)|
|Highest ranking||No. 5 (1933 U.S. ranking)|
|Grand Slam Singles results|
|French Open||QF (1933)|
|US Open||QF (1928, 1930, 1933, 1935, 1936)|
|Grand Slam Doubles results|
|Wimbledon||QF (1931, 1932)|
|US Open||F (1931)|
|Grand Slam Mixed Doubles results|
|Wimbledon||4R (1930, 1932)|
In 1931 Mangin, partnering compatriot Berkeley Bell, were runners-up in the doubles final of the U.S. National Championships, played in Brookline, MA, losing in straight sets to compatriots John Van Ryn and Wilmer Allison.
During WWII Mangin enlisted in the United States Army Air Forces (AAF). He became a tail gunner on the B-17 Flying Fortress and flew 50 missions over Europe. He was wounded twice in missions over Italy and France and shot down two ME-109s in a mission over Germany. Reaching the rank of staff sergeant he received the Distinguished Flying Cross (DFC), the Air Medal with six clusters and a Purple Heart with one cluster.
Grand Slam finals
Doubles (1 runner-up)
|Runner-up||1931||U.S. National Championships||Grass||Berkeley Bell|| John Van Ryn
|4–6, 3–6, 2–6|
- Lowe's Lawn Tennis Annual. London: Eyre & Spottiswoode. 1935. p. 218.
- USTA (1979). Bill Shannon, ed. Official Encyclopedia of Tennis (Rev. and updated 1st ed.). New York: Harper & Row. p. 254. ISBN 0060144785.
- "Sport: Tennis". Time. March 25, 1935.
- "Sutter and Mangin Added to U.S. Team". The New York Times. May 13, 1931.
- "Gregory Mangin, Wounded Twice As Tail Gunner, To Take Up Golf". The Miami News. September 3, 1944.