Oilliphéist

The Oilliphéist is one of the oldest creatures in Irish tradition — a vast serpentine monster whose name, from Old Irish, means simply 'great beast' or 'great worm'. Where most Irish lake and river monsters are creatures of local legend, the Oilliphéist belongs to a more ancient stratum: a primordial serpent woven into the mythology of the land itself.

The most persistent tradition links it to the creation of the River Shannon. As Saint Patrick drove the serpents from Ireland, the Oilliphéist fled westward, and its enormous body writhing through the limestone carved the course of the great river as it went — the landscape itself as scar of the monster's passing. Other accounts place it in specific loughs, where it waits in the cold dark far below the surface.

The Oilliphéist sits in a tradition that connects Irish water-monsters to the pre-Christian cosmology of serpents as embodiments of the underworld and the wild — the same ancient dread that underlies the Afanc in Wales and the Worm in northern England.