Derryth Lynne Thomas (born 29 September 1939 in Llanelli, Carmarthenshire) is a Welsh cricketer who played 10 Test matches for the England women's cricket team between 1966 and 1976 and 24 One-Day Internationals for England and the International XI between 1973 and 1982. She opened the batting for England when they won the 1973 Women's Cricket World Cup, and, playing for England against the International XI, became the first woman to score a century in one-day international cricket.
Along with Enid Bakewell, Thomas held the record for the highest opening run partnership in Women's Cricket World Cup history (246) until 2008. The cricket teams that she played for included Cardiff, Sussex Women, Glamorgan Women, and West Counties Women.
She also played hockey at international level for Wales. She was a full-time P.E. teacher at Neath Girls' Grammar School.