Owen Glendower: An Historical Novel by John Cowper Powys was first published in America in January 1941, and in the UK in February 1942. Powys returned to Britain from the United States in 1934, with his lover Phyllis Playter, living first in Dorchester, where he began work on his novel Maiden Castle. However, in July, 1935, they moved to the village of Corwen, Denbighshire, North Wales, historically part of Edeirnion or Edeyrnion, an ancient commote of medieval Wales that was once part of the Kingdom of Powys; it was at Corwen that he completed Maiden Castle (1936). This move to the land of his ancestors led Powys to write Owen Glendower the first of two historical novels set in this region of Wales; the other was Porius (1951). Owen, Powys's ninth novel, reflects "his increasing sense of what he thought of as his bardic heritage."

John Cowper Powys was an English novelist, philosopher, lecturer, critic and poet born in Shirley, Derbyshire, where his father was vicar of the parish church in 1871–1879. Powys appeared with a volume of verse in 1896 and a first novel in 1915, but gained success only with his novel Wolf Solent in 1929. He has been seen as a successor to Thomas Hardy, and Wolf Solent, A Glastonbury Romance (1932), Weymouth Sands (1934), and Maiden Castle (1936) have been called his Wessex novels. As with Hardy, landscape is important to his works. So is elemental philosophy in his characters' lives. In 1934 he published an autobiography. His itinerant lectures were a success in England and in 1905–1930 in the United States, where he wrote many of his novels and had several first published. He moved to Dorset, England, in 1934 with a US partner, Phyllis Playter. In 1935 they moved to Corwen, Merionethshire, Wales, where he set two novels, and in 1955 to Blaenau Ffestiniog, where he died in 1963.