King of Scotland, and father of Arthur’s warriors Dirmyg, Iustig, Edmyg, Angawdd, Gofan, Celyn, Conyn, Mabsant, Gwyngad, Llwybyr (Llwybar), Coch, Meilyg, Cynwal, Ardwyad, Ergyryad, Neb, Gildas, Calcas, Hueil, Gwarthegydd, Gwenabwy and Cywyllog.

As one of Culhwch’s tasks in Culhwch and Olwen, he had to obtain the tusk of the Chief Boar Ysgithyrwyn for the giant Ysbaddaden to trim his beard. Ysbaddaden would allow no one to bring him the tusk except Caw. Culhwch thus faced the additional task of convincing Caw to leave his kingdom and travel to Ysbaddaden’s fortress.

At the behest of Arthur, Caw accompanied the warriors on the hunt for Ysgithyrwyn, took the tusk, and shaved Ysbaddaden with it personally. He also accompanied Arthur on the search for the Black Hag and, after Arthur had killed her, collected her blood.

In the Life of St. Gildas, Arthur kills Caw’s son Hueil. Caw is said to be a giant and regarded as a saint.