Rachel Thomas OBE (10 February 1905 – 8 February 1995) was a Welsh character actress born in the village of Alltwen, near Pontardawe, in the Swansea Valley, Glamorgan. Raised by her aunt and uncle, she trained as a teacher, competed on the eisteddfod circuit, and was a reader at her church before turning to acting.
Thomas made her film debut in The Proud Valley (1940), starring alongside Paul Robeson, in which she first played the role that would define her career: the stoical, self-sacrificing Welsh "Mam" of the mining valleys. She went on to reprise variations of this role across a string of Welsh-set films, becoming one of the most recognisable faces of Welsh cinema.
Her other credits included Blue Scar (1949), Valley of Song (1953) and Tiger Bay (1959), and she remained a familiar figure in Welsh film and broadcasting throughout her career. In 1968 she was awarded the OBE for services to Wales, and in 1991 she received a special BAFTA Cymru award recognising her body of work.
Rachel Thomas became a Fellow of the Royal Welsh College of Music and Drama in Cardiff in 1993, two years before her death in 1995. She is remembered as one of the founding figures of Welsh-themed screen acting.