noun - The Afanc is a lake monster from Welsh mythology. Its exact description varies; it is described variously as resembling a crocodile, beaver or dwarf-like creature, and is sometimes said to be a demon. The lake in which it dwells also varies; it is variously said to live in Llyn Llion, Llyn Barfog, near Brynberian Bridge or in Llyn yr Afanc, a lake near Betws-y-Coed that was named after the creature.
Susan Cooper's The Dark Is Rising sequence features an afanc which inhabits Llyn Barfog. It is driven away by the son of King Arthur.
China Miéville's The Scar features a large afanc (spelled as avanc), bound by chains to tow the city of Armada across the oceans. The afanc in The Scar is of phenomenal size, so vast that to observers one vein on the creature's surface looks like a 20-foot (6.1 m) high ridge.
The Afanc plays a leading role in episode three of Merlin - it's a creature made of earth and water which can be destroyed by fire and wind. It poisons Camelot's water supply, causing a supernatural plague.
The Lord of the Rings Online features the afanc (here spelled as avanc) as a species of salamander-like beasts that dwell in and around bodies of water in Dunland. A tribe of swamp-dwelling Dunlendings subsist in part off the beasts, and call themselves the Avanc-luth.