- Source: Mary Duncan (disambiguation)
Mary Duncan (1894–1993) was an American stage- and film actress.
Mary Duncan may also refer to:
Mary Duncan (writer) (born 1941), American writer, publisher, and educator
Mary Ellen Duncan (1941–2022), American academic administrator and teacher
Mary Lundie Duncan (1814–1840), Scottish poet and hymnwriter
Mary Duncan, co-founder of W & M Duncan and Company
Mary Duncan Library, Benson, North Carolina
Mary Duncan, fictional character in The House by the Churchyard