Mary Bain (Karpatorussia, Hungary, August 8, 1904 - New York, October 26, 1972) was an American chess master.
She was a Women's World Chess Championship Challenger in 1937 and 1952 and the first American woman to represent the U.S. in an organized chess competition.
Bain was awarded the Woman International Master title in 1952 and represented her country at the 1963 Chess Olympiad, held in Split.
In international tournaments, she took fifth place at Stockholm 1937 (Vera Menchik won) and 14th place at Moscow 1952 (Elisabeth Bykova won).
Mary Bain won the U.S. Women's Chess Championship in 1951.