Arawn

In Insular Brythonic mythology, Arawn was the Lord of the Underworld, which was named Annwn.

Amaethon stole a dog, lapwing and a white roebuck from Arawn, leading to the Cath Godeau, which Arawn lost to Amaethon and his brother, Gwydion.

In the Mabinogion, Pwyll mistakenly set his hounds upon a stag, only to discover that Arawn had been hunting the same animal. To pay for his misdeed, Arawn asked him to trade places with him for a year and a day, and defeat Hafgan, Arawn's rival, at the end of this time, since Hafgan could only be killed by a mortal. Arawn, meanwhile, took Pwyll's place as king of Dyfed. Arawn and Pwyll became good friends because Pwyll did not sleep with Arawn's wife.

In Welsh folklore, Arawn rides with his white, red-eared hounds (the Cwn Annwn or Hounds of Annwn) through the skies in autumn, winter, and early spring. The baying of the hounds is identified with the crying of wild geese as they migrate, and the quarry of the hounds are the souls of the damned, being chased back to Annwn (sometimes to the abode of the Brenin Llwyd or Grey King).