The Fisher King is a figure in Arthurian legend, the last in a long line of British kings tasked with guarding the Holy Grail. The Fisher King is both the protector and physical embodiment of his lands, but a wound renders him infertile and his kingdom barren. Unable to walk or ride a horse, he is sometimes depicted as spending his time fishing while he awaits a "chosen one" who can heal him. Versions of the story vary widely, but the Fisher King is typically depicted as being wounded in the groin, legs, or thigh. The healing of these wounds always depends upon the completion of a hero-knight's task.

Most versions of the story contain the Holy Grail and the Lance of Longinus as plot elements. In some versions, a third character is introduced; this individual, unlike the hero-knight archetype, is ignorant of the King's power, but has the ability to save the king and land, or to doom it. Variations of this third party give us divergent legends.

As a literary character, the Fisher King originates in Chrétien de Troyes' unfinished writings of the adventures of Perceval. Many authors have endeavoured to complete and extend the work, resulting in various continuations. Major sources of the legend include Chrétien's Li Contes del Graal; Perceval, ou Le Conte du Graal (c. 1160-1180), Wauchier de Denain's First Continuation (c. 1180-1200), Robert de Boron's Didot-Perceval (c. 1191-1202), Peredur son of Efrawg (c. 1200), Perlesvaus (c. 1200), Wolfram von Eschenbach's Parzival (c. 1217), and Thomas Malory's Morte D'Arthur (c. 1400).