Gwethalyn Graham (January 18, 1913 – November 25, 1965) was a Canadian writer, whose 1944 novel Earth and High Heaven was the first Canadian book to reach number one on the New York Times Best Seller list. Graham won the Governor General's Award twice, for her first novel Swiss Sonata in 1938, and for Earth and High Heaven in 1944.
She was born Gwethalyn Graham Erichsen-Brown, to wealthy Toronto parents. Her father was a lawyer. At 19, she was a student at Smith College in Massachusetts, but dropped out and eloped with John McNaught, the son of her father's business partner. They later divorced, and Graham moved to the city of Westmount, on the Island of Montreal where she became a close friend and associate of Hugh MacLennan, F. R. Scott, Thérèse Casgrain and Pierre Trudeau. Graham subsequently married David Yalden-Thomson, a philosophy professor at McGill University; they subsequently also divorced.
Graham was also an outspoken activist against anti-Semitism and anti-French Canadian discrimination; Earth and High Heaven depicted an interfaith romance between a Protestant woman from Montreal and a Jewish man from Northern Ontario. The novel was optioned by Samuel Goldwyn for a film that was to star Katharine Hepburn; however, the film was never made.
Graham died in 1965 of an undiagnosed brain tumour, aged 52.
Graham's sister, Isabel LeBourdais, was a journalist whose 1966 book The Trial of Steven Truscott played a key role in disputing the evidence that led to Steven Truscott's controversial murder conviction.
Both Swiss Sonata and Earth and High Heaven were reissued by Cormorant Books in 2004.
Graham is the subject of a biography Gwethalyn Graham: a Liberated Woman in a Conventional Age by Barbara Meadowcroft (Toronto: Women's Press, 2008).