A knight of the Round Table. Sir Kay is one of the oldest elements in the Arthurian tradition. In the early Celtic tales, such as Culhwch and Olwen, Kay (spelled "Cei") is King Arthur's right-hand man and best knight, mighty in battle and embued with supernatural powers. In the later French romances, Kay was said to be Arthur's foster brother, and evolved into a surly, often incompetent foil to other, more heroic knights, who only kept his high place in Arthur's court thanks to nepotism.