Mary Long

Mary Long may refer to:
 * Mary Beth Long (born 1963), American businesswoman and former U.S. government official
 * Mary Elitch Long (1856–1936), one of the original owners of Elitch Gardens in Denver, Colorado
 * Mary "Polly" Long, first wife of Tobias Lear V
 * "Mary Long", a song by Deep Purple from their 1973 album Who Do We Think We Are