The Welsh god of the underworld. The god Amaethon stole from him a dog, lapwing and roebuck with led to the Battle of the Trees, in which his forces were defeated. A tale in the Mabinogion relates how he persuaded Pwyll to trade places with him for the span of a year and a day. In this period, Pwyll defeated Arawn's rival for dominion of the underworld Hafgan. Because Pwyll also refrained from sleeping with Arawn's wife, they became close friends.