Nofelydd Seisnig oedd Mary Florence Elinor Stewart (née Rainbow; 17 Medi 1916 – 9 Mai 2014) sy'n fwyaf enwog am ei chyfres Merlin sy'n cyfuno'r nofel hanesyddol gyda ffantasi.
Ganwyd Mary yn Sunderland, Lloegr a derbyniodd ei haddysg ym Mhrifysgol Durham. Priododd yr ysgolhaig Syr Frederick Stewart ym 1945 (bu farw 2001).
Nofelau
Cyfres Myrddin
- The Crystal Cave (1970)
- The Hollow Hills (1973)
- The Last Enchantment (1979)
- The Wicked Day (1983)
- The Prince and the Pilgrim (1995)
Llenyddiaeth plant
- The Little Broomstick (1971)
- Ludo and the Star Horse (1974)
- A Walk in Wolf Wood (1980)
Eraill
- Madam, Will You Talk? (1954)
- Wildfire at Midnight (1956)
- Thunder on the Right (1957)
- Nine Coaches Waiting (1958)
- My Brother Michael (1959)
- The Ivy Tree (1961)
- The Moon-Spinners (1962)
- This Rough Magic (1964)
- Airs Above the Ground (1965)
- The Gabriel Hounds (1967)
- The Wind Off the Small Isles (1968)
- Touch Not the Cat (1976)
- Thornyhold (1988)
- Stormy Petrel (1991)
- Rose Cottage (1997)
