A legendary lake monster whose name, in modern Welsh, means 'beaver'. This would appear to be consistent with the watery connections usually applied to this mythical creature. The word addanc, when employed as a noun rather than a proper noun, has also been used simply to refer to a spirit that dwells in a watery location, and not an actual creature. In this case the spirit is not an animal, but has a more human appearance. There is, however, no description of the Addanc in either form. The cognate Irish word abhac (dwarf) is derived from ab, modern abha, a river; J. Vendryes claims it originally signified a spirit inhabiting waters.
No descriptions can be found of the monster's appearance. It was strong and was attracted to comely damsels. Sometimes attributed with magical powers and also the ability to speak Welsh. In the fifteenth century, a poet claimed an afanc lived in Llyn Syfaddon, now Llangorse Lake in Powys.
In a tale where Percivale is the hero, the afanc resides in a cave near the Palace of the Sons of the King of Tortures. The name of the palace derives from the neverending cycle of the afanc killing the three sons, who were chieftains, of the king every day, and they get resurrected by the maidens of the court. The three sons were to seek out the afanc and Percivale asks to ride with them, but they declined because if he were to be killed, they would not be able to resurrect him.
Percivale, wishing for fame and honour by killing the beast, decides to continue on the journey alone. He meets a lady who states the afanc will slay him since the beast is invisible and kills with poison darts. The woman, the Empress of Constantinople, gave him an adder stone which rendered him invisible to it, and Percivale pledged his undying love towards her.
This afanc devoured maidens and it appears to have had manipulative skills, for it hurled poisoned spears and other missiles at anyone who tries to enter its cave. Peredur entered the cave, pierced the afanc with the stone and beheads it (or just kills it with a spear). The three sons arrive and state it was predicted that Percivale would kill the creature.
Another story tells how Hu Gadarn slew such a creature, but this tale is a late concoction as Hu Gadarn may have been invented to Iolo Morgannwg (1747-1826), who claimed that Hu Gadarn had led the Britons to Britain from Sri Lanka.
Llyn yr Afanc | The Legend of King Arthur