Geoffrey Thomas Leslie Ashe (29 March 1923 – 30 January 2022) was a British cultural historian and lecturer, known for his focus on King Arthur. Born in London, Ashe was an only child who excelled all his classmates in academics. Periods of poor health meant that he had ample opportunity to read broadly, or be read to. Through his parents, he developed a life-long enjoyment of Gilbert & Sullivan's operas and Conan Doyles' Sherlock Holmes canon. His mother read some of Conan Doyle's stories to him from the Strand when they were first published; his father took him to see Gilbert & Sullivan performances by some of the cast who had worked with Gilbert himself. Ashe's father was general manager of Poly Tours, later Lunn-Poly, and travelled to Europe and the British Isles frequently with his parents to the hotels used by the agency, sometimes to correct problems, sometimes to establish business contacts. His favourite childhood memories were of summers spent in the West Highlands of Scotland, at the Highland Hotel in Fort William. When he was 16, his parents emigrated to Vancouver, British Columbia. He graduated from the University of British Columbia before continuing at Trinity College, Cambridge. Many of his historical books are centred on factual analysis of the Arthurian legend, and the archaeological past of King Arthur, beginning with his King Arthur's Avalon: The Story of Glastonbury, in 1957. The book was inspired by what Ashe had read in G. K. Chesterton's Short History of England. He is a major proponent of the theory that the historical King Arthur was Riothamus, presented in an article in Speculum, April 1981, and expanded in The Discovery of King Arthur (1985) and in various further articles. His fresh idea was to scrutinise Arthur's foreign campaigns in Geoffrey of Monmouth's account and take the material seriously, concluding that, though the legendary Arthur is a composite figure, the career of Riothamus seems to underlie at least a major portion of Geoffrey's account, for which Ashe adduces passages in a Breton text and several chronicles.