Arawn

In Welsh mythology, Arawn was the Lord of the Underworld, which was called Annwn.
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Noun
1. Celtic deity who was the lord of Annwfn (the other world or the land of fairies)
(hypernym) Celtic deity
(classification) Wales, Cymru, Cambria

[Celtic] 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.