Oilliphéist

Also Known As: Irish ollphéist, plural ollphiasta; also written ollpheist, ollipheist, uilepheist
Region/Culture: Northern Europe
Mythos: Irish Mythology, Celtic Mythology
Primary Type/Nature: Monsters and Beasts
Mythical Attributes: An ollphéist is a water-beast of enormous bulk whose body is heavy enough to carve river channels and whose appetite runs to whole herds of cattle.
Role in Mythos: It is the standing adversary of Irish saints and heroes, the wild thing that has to be driven out, chained or killed before a lake or a valley belongs to people.
Relation to Humans: Humans lose livestock to it and occasionally their lives, and the stories are usually about someone finally putting a stop to that. A surprising number of the tellings are comic rather than fearful, with the beast outwitted, disgusted or simply annoyed into surrender.

The water in an Irish lake turns black about four feet down. Below that, something the length of a barge could lie the whole summer and nobody on the shore would be any the wiser. That is the quiet assumption underneath a great many Irish stories: cattle counted in the evening and short by morning, a swell crossing flat water with no wind behind it, a grandfather who saw something in the 1840s and would not be drawn on what.

Ollphéist is not one animal’s name. It is two ordinary Irish words shoved together, oll for great and péist for worm, beast, reptile, and it is applied to whatever long, heavy, wrong thing is understood to be living in a particular stretch of fresh water. The Irish dictionaries still keep péist for humbler things, the worm in an apple, the worm in a dog, which means the horror is a scaling-up rather than an invention. Take the thing at the bottom of the compost heap and make it forty feet long and put it in the lake where the children swim.

They were everywhere. Ireland has an enormous number of lakes for its size, and a strikingly large number of them had a resident. When schoolchildren across the Free State were sent home in 1937 and 1938 to write down whatever the old people still knew, the péist came back to the classrooms lake by lake, parish by parish, in copybook handwriting. The name changes a little from county to county. The shape of the story rarely does. Something enormous is in the water, and once upon a time somebody dealt with it.

The most repeated of those dealings runs through the biggest river in the country. Word reaches an ollphéist that Patrick has landed and intends to clear the island of serpents, and the beast does not wait to argue the point. It goes, at speed, west and south toward the Atlantic, and its body ploughs a trench through the soft middle of Ireland as it flees. Water fills the trench behind it. That trench is the Shannon, and the Shannon does not run straight, which the story treats as evidence rather than coincidence.

Attached to that flight is one of the great comic set pieces of Irish folklore. Somewhere along the way the monster swallows a piper named Ó Ruairc, who is drunk enough that he either fails to notice or declines to care. Inside the beast he keeps playing. The pipes are not a soft instrument at the best of times, and in a confined space with poor acoustics and no way of stopping the man, the ollphéist holds out for as long as it can and then coughs him out onto the bank, still playing. The tale has survived a very long time on the strength of its punchline. Somewhere in Ireland, the joke goes, there is a creature that could swallow a bullock whole and was defeated by a musician.

Not all of them are funny. In Donegal the ollphéist is Caoránach, and she is called the mother of demons. The older, Fenian version of her origin is unpleasant in a way the saints’ legends are not: Fionn mac Cumhaill and the Fianna kill a hag, and when they find her body they are warned to leave her thighbone alone. Conán breaks it anyway. What comes out is small and hairy and no cause for alarm for about as long as it takes to grow, and then it is in the lake, and then the cattle of Ulster start disappearing. The people blame Conán, which is fair, and Conán goes into the creature’s mouth with a blade and finishes what he started from the inside. In the Christianised telling, Patrick does the killing. Either way the blood runs out into the water and stains the rocks red, and that is why the lake is Lough Derg, the red lake. The island in it became St Patrick’s Purgatory, and pilgrims have been walking barefoot on those stones ever since, on ground certified by a dead monster.

There are tellings in which the killing does not take. Patrick fights the thing, fails, and settles for confining it. In those versions Caoránach is still down there.

What an ollphéist can do follows directly from what it is. Its power is mass. It does not need fire, or venom, or a curse; it needs only to be very large in a country of shallow water and soft ground, where an animal of that size can reroute a river simply by leaving in a hurry, and can drain a townland of its livestock by feeding normally. It belongs to the water and keeps to it, and the water hides it completely, which is the closest thing it has to cunning.

The limits are just as plain. Out of the lake it is slow and enormously conspicuous. It can be reached with a blade, and it dies of ordinary wounds when someone is brave or stupid enough to get close, sometimes from the inside, which is a strange recurring detail. It has no answer at all to holiness, and the whole class of them was written into Irish tradition largely so that Patrick would have something to drive out of an island that has no snakes. And at least one of them was beaten by a drunk with a set of pipes.

Frequently Asked Questions

What is an Oilliphéist?

An oilliphéist, or ollphéist, is a giant serpentine water monster of Irish folklore. The name is simply Irish for “great worm” or “great beast,” and it was applied to the creatures believed to live in Ireland’s lakes and rivers rather than to one individual animal. Stories of saints and heroes killing or banishing them are found across the country.

How did the Oilliphéist create the River Shannon?

In the best-known tale, an ollphéist hears that Saint Patrick has arrived in Ireland to drive out serpents and flees toward the sea. Its huge body gouges a channel through the ground as it goes, and water fills the channel behind it. The result is the winding course of the River Shannon.

What happened to the piper swallowed by the Oilliphéist?

A drunken piper named Ó Ruairc was swallowed whole and kept playing inside the monster’s stomach, either unaware of his situation or unbothered by it. The ollphéist eventually found the noise unbearable and coughed him back up. He survived, still playing.

Who was Caoránach?

Caoránach was an ollphéist of County Donegal, called the mother of demons. In the Fenian version she emerges as a small hairy worm from the broken thighbone of a dead hag and grows until she is devouring the cattle of Ulster; in the Christian version Saint Patrick destroys her. Her blood is said to have reddened Lough Derg and given the lake its name.

How do you kill an Oilliphéist?

The stories give it no supernatural defences. It is killed with a weapon, frequently by someone who gets inside its mouth and strikes from within, or it is banished and bound by a saint rather than killed outright. In several tellings the binding is all that anyone manages, and the creature is understood to be in the lake still.