9. The Cyhyraeth/Gwrach y Rhibyn could be one of the most frightening demons of all; many accounts describe it looking like a corpse and sounding like death.
The Cyhyraethis the Welsh equivalent of the Irish Banshee. The name”cyhyraeth” refers to the creature’s corpse-like appearance for it incorporates the Welsh words for flesh and bone. Thus the Cyhyrarth was a ghastly looking wraith, pale and wasted which appeared to foretell death. It would do this not by its physical manifestation but by the dreadful moaning of its voice. For the Cyhyraeth had a voice like a person dying. She would cry out three times before a person passed away due to a disaster or epidemic- even if they are miles away from their original home.
Closely related to the Cyhyraeth was the “Hag of the Mist” or Gwrach y Rhibyn. Also a death spirit, the Hag would take the form of a desiccated harpy of, particularly unpleasant appearance. As well as pale leathery wings, the hag had long straggly hair and black teeth. She specifically targeted those due to die at night. Then, she would creep to their window and moan their name through the window panes. Or, if they were abroad, she would walk beside them, traveling invisibly or as a nearby mist. Sometimes, however, the hag would be seen at a river or stream, washing her hands- hence her association with the washer at the ford.
Other Celtic demons haunted the natural landscape.