A hound that belonged to Greid.
As one of his tasks, the warrior Culhwch had to obtain this hound to hunt the boar Twrch Trwyth. In addition, the hound had to be managed by the houndsman Mabon, and had to be held with the leash of Cors Hundred Claws, the collar of Canhastyr Hundred Hands, and the chain of Cilydd Hundred Holds.
Arthur himself obtained the hound on Culhwch’s behalf, and used him in the hunting of the boars Ysgithyrwyn and Twrch Trwyth.
Source
Culhwch and Olwen | Late 11th century