Mary Adela Martin (née Balmford) (16 January 1907 in Folkestone – 9 October 1969 in London) was a British sculptor best known for her work with her husband Kenneth Martin.
Mary Balmford studied at Goldsmiths' College, London in 1925–9 and at the Royal College of Art 1929–32 where she met and married Kenneth Martin in 1930. Exhibited at the A.I.A. from 1934, mainly as a still-life and landscape painter, using her maiden name. During the war Mary taught drawing, design and weaving at Chelmsford School of Art 1941–4 but gave this up when she became pregnant with her first child. Along with her husband, Mary Martin moved towards pure abstraction in the late 1940s painting her first abstract picture in 1950, made her first reliefs in 1951 and her first free-standing construction in 1956. Kenneth and Mary collaborated on the Environment section of the seminal exhibition This Is Tomorrow. Mary Martin participated in group exhibitions of constructed art in England and abroad, notably Konkrete Kunst, Zürich 1960, and Experiment in Constructie, Stedelijk Museum, Amsterdam, 1962. Martin designed a screen for the Musgrave Park Hospital in Belfast (1957), reliefs for the Orient Line's S.S. Oriana (1960) and a wall construction for the University of Stirling.
Martin was the joint winner of the 1969 John Moores Painting Prize.