Canthrig Bwt

In the folklore of the Llanberis Pass, Canthrig Bwt was a giantess who was also a witch — a figure feared throughout the district around Nant Peris for her taste for children. Tradition places her lair beneath a great stone close to Pont-y-Cromlech, the old bridge partway along the pass, where she was said to lie in wait for unwary youngsters.

According to the story, Canthrig had sold her soul to the devil and developed a particular appetite for the brains of children, snatching victims from the surrounding farms until a number had disappeared. Eventually a young man came forward to confront her, arming himself with an iron sword and securing the blessing of both a Christian monk and a 'white' (benevolent) witch before going after her.

The confrontation ended with Canthrig seized by the arm and beheaded with a sickle; she is said to have been buried afterwards near a place called Tir Coch, not far from Llanberis. The tale, sometimes dated by storytellers to the fourth century, remains one of the best-known pieces of 'cannibal witch' folklore in Gwynedd, and Pont-y-Cromlech is still pointed out to walkers in the pass as her former haunt.