|Born||Mary Florence Elinor Rainbow
September 17, 1916
Sunderland, County Durham, England
|Alma mater||Durham University|
|Spouse(s)||Sir Frederick Stewart|
Mary Florence Elinor Stewart (née Rainbow; born 17 September 1916) is a popular English novelist, best known for her series about Merlin, which straddles the boundary between the historical novel and the fantasy genre.
Stewart was born in Sunderland, County Durham, England and graduated from Durham University, from where she received an honorary D.Litt in 2009. She was a lecturer in English Language and Literature there until her marriage in 1945 to Sir Frederick Stewart, former chairman of the Geology Department of Edinburgh University. Sir Frederick died in 2001. 
She is also the author of many crime fiction, gothic fiction and romance novels, several of which have been adapted for television and/or film. Several of her books are set in Scotland; others are set in more exotic locations such as Damascus, the Greek islands, Spain, France, Austria, etc.
She was at the height of her popularity in the 1960s and 1970s when many of her suspense and romantic novels were translated into many languages. Stewart is considered one of the founders of the romantic suspense subgenre, blending romance novels and mystery. Her novels seamlessly combined the two genres, maintaining a full mystery while focusing on the courtship between two people. In her novels, the process of solving the mystery "helps to illuminate" the hero's personality, helping the heroine to fall in love with him.