A (; plural "old man; rustic, churl, lout"; Old Irish ) is a trickster or bogeyman figure in Gaelic folklore and mythology. The "old man" is paired with the "hag, old woman" in Irish legend.
(Old Irish also ) is the Irish word for a tenant, a serf or peasant. It is derived from (Old Irish ) "tail, penis".
The word has alternatively been derived from both "cottage, hut" (probably a borrowing from Old Norse, as is English booth). The term "tenant farmer" is thus equivalent to a cotter (the of the Domesday Book); a was a half-free peasant of a lower class. In either case, the name is formed by the addition of nominal suffix ("connected or involved with, belonging to, having").
In modern Gaelic, simply means "old man", often used affectionately.
In the , one " the Eternal" is king of Mag Mell. This name is derived from "victorious" and unrelated to in origin. However, the two names may have become associated by the early modern period, as Manannan is also named king of Mag Mell, and the figure in (17th century) is in turn identified with Manannan.
In modern Gaelic (Scottish and Irish) folklore, the or "old man" becomes a type of bugbear, to the point of being identified with the devil.
In the early modern (16th or 17th century) tale , the is identified with the . This identification inspired Lady Gregory's tale "Manannan at Play" (Gods and Fighting Men, 1904), where Manannan makes an appearance in disguise as "a clown ... old striped clothes he had, and puddle water splashing in his shoes, and his sword sticking out naked behind him, and his ears through the old cloak that was over his head, and in his hand he had three spears of hollywood scorched and blackened."
In Scottish folklore the comes down the chimney to kidnap naughty children, used as a cautionary tale or bogeyman figure to frighten children into good behaviour. A related being known as the ("Old Grey Man") is considered an omen of death. In Walter Scott's novel, Waverley, Fergus Mac-Ivor sees a , which foretells his death. In W. B. Yeats's 1903 prose version of The Hour-Glass, the character of the Fool remarks at one point during the play that a he met upon the roadside attempted to trick him with a riddle into letting the creature near his coin.