Mary Emelia Mayne (31 December 1858 – 12 August 1940), was an Australian philanthropist.
Born in Brisbane, Queensland, Australia, Mary Emelia Mayne was the second youngest of five children of Irish parents, Patrick Mayne, a butcher and grazier, and his wife Mary McIntosh Mayne. She attended All Hallows' School, a Catholic girls' school in Brisbane, until 1877. Thereafter she oversaw and hostessed many functions at Moorlands, the family home at Auchenflower. She and her siblings all inherited real estate, giving them independent means. Neither she nor her siblings would marry.
James O'Neil Mayne (28 January 1861 – 31 January 1939), one of her brothers, attended Brisbane Grammar School, graduated with a B.A. from the University of Sydney in 1884, and studied medicine at University College London, receiving the qualifications of Licentiate of the Royal College of Physicians (LRCS) and Membership of the Royal College of Physicians (MRCS) in 1890. James Mayne worked as a doctor at the Brisbane General Hospital from 1891 until 1898. James O'Neil Mayne died at Moorlands.
The Mayne family made Moorlands available to the Red Cross working parties during World War I, and contributed to the Anglican St Martin's War Memorial Hospital.