Arawn is the king of Annwn, the Welsh Otherworld, equated with Gwynn ap Nudd of southern Wales. In the story of Pwyll, he appeared as a hunter in gray on a large, pale horse with a pack of white dogs with red ears. Out hunting with his own dogs, Pwyll saw Arawn’s hounds chasing down a white stag. Chasing the white hounds off, he set his own animals on the cornered stag, but was rebuked by Arawn for his discourtesy. To atone for his rudeness, Pwyll, the prince of Dyfed, agreed to exchange shapes for a year. During his reign as Arawn, he defeated Arawn’s enemy Hafgan. Also during his type masquerading as Arawn, Pwyll had access to Arawn’s wife, but abstained. Even after they returned to their respective kingdoms, they remained good friends. Upon Pwyll’s death, Arawn sent a gift of pigs to Pryderi, Pwyll’s son.
For the theft of one of Arawn’s dogs, a roebuck, and a lapwing by Amaethon, Arawn fought the sons of Don in the Cath Godeu, Battle of Trees. Later, King Arthur stole a magic cauldron from him, possibly synonymous with the Holy Grail. The cauldron had rejuvenating powers and would not boil a coward's food.