The Hag of the mist, known in Welsh

Welsh language

Welsh is a member of the Brythonic branch of the Celtic languages spoken natively in Wales, by some along the Welsh border in England, and in Y Wladfa...

 as the Gwrach-y-Rhibyn
or the Cyoeraeth, is a hag

Hag

A hag is a wizened old woman, or a kind of fairy or goddess having the appearance of such a woman, often found in folklore and children's tales such as Hansel and Gretel. Hags are often seen as malevolent, but may also be one of the chosen forms of shapeshifting deities, such as the Morrígan or...

 spirit comparable to the Irish

Irish mythology

The mythology of pre-Christian Ireland did not entirely survive the conversion to Christianity, but much of it was preserved, shorn of its religious meanings, in medieval Irish literature, which represents the most extensive and best preserved of all the branch and the Historical Cycle. There are...

 banshee

Banshee

The banshee , from the Irish bean sí is a feminine spirit in Irish mythology, usually seen as an omen of death and a messenger from the Otherworld....

. Like the banshee, the Hag of the mist is portrayed as an ugly woman, whose shriek or cry is said to forewarn of misfortune or death.

Often invisible, she can sometimes be seen at a crossroads or stream when the mist rises.

Her shriek warns of coming misfortune or even death. If it is death that is coming, the name of the one doomed to die will be heard in her "shrill tenor". The misfortune may be coming to the person hearing her voice, or to someone in their family.