This is the first comprehensive authoritative survey of Arthurian literature and traditions in the Celtic languages of Welsh, Cornish, Breton, Irish and Scottish Gaelic. With contributions by leading and emerging specialists in the field, the volume traces the development of the legends that grew up around Arthur and have been constantly reworked and adapted from the Middle Ages to the twentieth century. It shows how the figure of Arthur evolved from the leader of a warband in early medieval north Britain to a king whose court becomes the starting-point for knightly adventures, and how characters and tales are reimagined, reshaped and reinterpreted according to local circumstances, traditions and preoccupations at different periods. From the celebrated early Welsh poetry and prose tales to less familiar modern Breton and Cornish fiction, from medieval Irish adaptations of the legend to the Gaelic ballads of Scotland, Arthur in the Celtic Languages provides an indispensable, up-to-date guide of a vast and complex body of Arthurian material, and to recent research and criticism.