A son of Caw and brother of Gildas. The Vita Gildae calls him Cuillus and describes him as valde strenuum in armis virum ('a man strong in war'). He is one of the Three Diademed Men of the Island of Britain. As one of Arthur's warriors he was known to 'never submit to a lord's hand'.
According to Culhwch and Olwen, he was an opponent of Arthur who eventually had him executed. Their feud began when Arthur stabbed Gwydre, Hueil's nephew, and also one of Arthur's warriors. In one tale, he and Arthur fought and Arthur was wounded in the knee. Arthur told Hueil he would not slay him, provided Hueil never mentioned the wound. Some time later Hueil forgot his promise and Arthur had him executed.
Another version of this story says that Arthur and Hueil, son of Kaw of Brydyn (Caw), fought over the favours of a lady. The were both wounded and went their separate ways, but Arthur always limped after this incident. Some years later they met again, and, even though Arthur was in disguise, Hueil recognised him by the limp. They fought again over the same lady. Arthur managed to throw Hueil against a large stone and, drawing his sword, cut off his head. Gerald of Wales tales us about a legend in which Gildas throws all books praising Arthur into the sea after Arthur's murder of his brother, Hueil.
Caradocís Vita Gildae recounts how Hueil, who had aspriations for the British throne, led raids into Britain from Scotland. Arthur tracked him down and killed him at the island of Minau, then had to beg for the forgiveness of St. Gildas, Hueilís brother.
Minau | The Legend of King Arthur
The stone in Ruthin, Clwyd, on which Arthur was said to have beheaded Hueil.