In Brythonic mythology, the Cwn Annwn ("hounds of Annwn") were the white, red-eared ghostly hounds of Annwn, the land of the dead. They were associated with the Wild Hunt, presided over by either Arawn or Gwynn ap Nudd.

In Wales, they were associated with migrating geese. They are supposed to hunt on specific nights (eves of St. John, St. Martin, Saint Michael the Archangel, All Saints, Christmas, New Year, St. Agnes, St. David, and Good Friday), or just in the autumn and winter. Some say that Arawn only hunts from Christmas to Twelfth Night.

Arawn and the hounds are sometimes accompanied by a fearsome hag calld the Mallt-y-Nos, Matilda of the Night.

Alternative: Cwn Mamau ("hounds of the mothers"), Gabriel Hounds (England), Ratchets (England), Yell Hounds, Isle of Man