The Grey King is a contemporary fantasy novel by Susan Cooper, published almost simultaneously by Chatto & Windus and Atheneum in 1975. It is the fourth of five books in her Arthurian fantasy series The Dark is Rising.The Grey King won the inaugural Tir na n-Og Award from the Welsh Books Council as the year's best English-language children's book with an "authentic Welsh background". It is set in Wales and incorporates Welsh folklore as well as Arthurian material.