Twrch Trwyth (Welsh pronunciation: [tuːɾχ tɾʊɨθ]; also Latin: Troynt (MSS.HK); Troit (MSS.C1 D G Q); or Terit (MSS. C2 L)) is an enchanted wild boar in Arthurian legend, which King Arthur or his men pursued with the aid of Arthur's dog Cavall or Cafall (Latin: Cabal).
The names of the hound and boar are glimpsed in a piece of geographical onomasticon composed in Latin in the 9th century (Historia Brittonum). But a richly elaborate account of the great hunt appears in the Welsh prose romance Culhwch and Olwen, probably written around 1100 AD. A passing reference to Twrch Trwyth also occurs in the elegy Gwarchan Cynfelyn preserved in the Book of Aneirin.
The name in Welsh can be construed to mean "the boar Trwyth", and may have its analogue in the boar Triath of Irish mythology (see #Etymology and Irish cognate below).
The earliest reference to the boar Trwyth occurs in a tract called De Mirabilibus Britanniae (or Mirabilia in shorthand), variously titled in English as "Wonders of Britain," etc. The Mirabilia is believed to be near-contemporaneous to the 9th-century Historia Britonum and is found appended to it in many extant manuscripts. It gives a list of marvels around Britain, one of them being the footprint left in rock by Arthur's dog Cavall (here Latinized as Cabal), made while chasing the great boar (here called Troynt):