Irish mythology is full of creatures — and most of them are nothing like the versions you’ve seen in films or on merchandise. The fairy folk of Irish tradition are not cute. They are dangerous, unpredictable, and governed by rules that humans ignore at their peril.
This page is divided into two sections. Creatures from Myth come from the earliest manuscripts — the formal stories of the gods and heroes. Creatures from Folklore are the beings that ordinary Irish people actually believed in, in their homes and on the roads. The distinction matters. This page will be continually updated.
Creatures from Myth
These creatures appear in the oldest Irish texts — stories written down by monks from the 7th century onward, drawing on traditions much older still. You’ll find them burning halls at Samhain, haunting battlefields, and requiring heroes to stop them.
Aillen | Aillén
A creature of the Tuatha Dé Danann who came to Tara every Samhain and burned it to the ground. He put every warrior to sleep with enchanted music first, then set the hall on fire. He did this for nine years in a row. It was the young Fionn mac Cumhaill who finally killed him, using a magic spear to stay awake through the music.
Bean Sídhe | Bean Sí
The supernatural woman of the fairy mounds whose cry announced a death. In the oldest sources she is not a ghost — she is a messenger, one of the Otherworld women connected to specific noble families. She didn’t cause death. She mourned it before it happened. Her cry meant one of the old bloodlines was about to lose a member.
Crom Cruach | Crom Crúch
A great idol that stood on the plain of Magh Slécht in Co. Cavan, surrounded by twelve stone figures. The early texts say the Irish once sacrificed firstborn children to it in exchange for good harvests. St. Patrick is said to have destroyed it. The stone where it stood was still pointed out centuries later.
Ellan Trechend | Elathan Trí Cheann
A three-headed monster that came out of a cave in the hills of Connacht and laid waste to Ireland until the warrior Cú Roí killed it. Its name means “the three-headed one.” It doesn’t get a lot of space in the early texts, but it left a mark — a reminder that the landscape of Irish mythology was full of things that lived underground and came up to cause trouble.
Luchtigern | Luchtigéarn
The Mouse Lord — which sounds harmless, but was actually a monstrous supernatural cat that lived in what is now Dunmore Cave in Co. Kilkenny. The Book of Leinster records that a female warrior named Aithbel went in and killed it. Dunmore Cave is listed in the old texts as one of the three darkest places in Ireland. That reputation outlasted the creature: in 928 AD, a Viking force killed over a thousand people sheltering there. The bones of forty-four victims have been found deep in the passages.
Lucharáchán | Lucharáchán
The original form of what later became the leprechaun. In the old texts the lucharáchán was a small supernatural being connected to hidden treasure — sometimes described as a water sprite. The comic shoemaker of later tradition came much later. The original was less friendly and considerably harder to deal with.
Na Bocanaigh | Na Bocánaigh
Supernatural beings that haunted battlefields — howling, shrieking creatures that rose around the dead and dying and fed on the chaos of slaughter. They are listed in the old texts alongside the Badb and the other war goddesses as part of the dark machinery that made Irish warfare so feared.
Na Peisteanna | Na Peisteanna
The great serpents and lake monsters of Irish myth — na peisteanna just means “the beasts.” Ireland’s lakes and rivers were understood to be full of them, and killing or driving them out was a standard task for heroes and saints alike. St. Patrick’s famous expulsion of the serpents is the best-known version of a theme that goes back much further.
Púca | Púca
A shapeshifting spirit that appears in both the earliest manuscripts and later folklore — one of the few creatures that bridges both traditions. In its mythological form it is darker and less predictable than the mischievous trickster of the folk tales. It could take the form of a horse, a goat, or a dark-furred creature, and its intentions were rarely clear until it was too late.
Werewolves of Ossory | Conriocht
The Irish werewolf tradition is older and stranger than the European version. The best-documented case involves a clan from what is now Co. Kilkenny who were cursed to become wolves for seven years at a time, two by two, generation after generation. Unlike European werewolves, they kept their human minds while in wolf form and could speak. The story was written down by Giraldus Cambrensis in the 12th century, but he said he was recording an ancient tradition.
Creatures from Folklore
These are the beings that ordinary people actually believed in — not figures from learned manuscripts, but things whispered about at crossroads and kitchen tables. They weren’t entertainment. They were explanations for why things went wrong. Many of these beliefs were held within living memory. Some still are.
Abhartach | Abhartach
A malevolent dwarf chieftain from ancient Ulster who refused to stay dead. He rose from his grave and drank the blood of his subjects until a hero finally pinned him underground with a sword of yew. He is one of the oldest undead figures in Irish tradition, and one of the earliest to be linked by scholars to vampire mythology.
Cat Sídhe | Cat Sí
A large black cat with a white spot on its chest, believed to be a witch in animal form. It could steal the soul of a dead person before the gods claimed it — which is why wakes were held with so much vigilance. The purpose of the wake wasn’t just to mourn. It was to keep the cat away from the body.
Changeling | Iarlais
A fairy substitute left in place of a stolen human child. The changeling looked like the child but was sickly, shrunken, and impossible to satisfy. It was one of the most widespread beliefs in Irish folklore and, tragically, was sometimes used to explain why a child failed to thrive or develop normally.
Clurichaun | Clúracán
A bad-tempered night creature found raiding wine cellars and riding animals across fields after dark. Some say the Clurichaun is just a leprechaun who has had too much to drink. Others insist they are entirely different beings with entirely different temperaments. The debate has never been settled.
Cú Sídhe | Cú Sí
A huge fairy hound — dark green, the size of a young bull — that hunted silently. The only sound it made was three bays, heard for miles around. Hearing the first bay meant danger. Hearing the third meant it was already too late.
Dearg Due | Dearg Dú
One of Ireland’s oldest vampire figures. A beautiful woman who died of a broken heart and rose from her grave to take revenge on men. Her name means “red blood sucker.” Her grave in Co. Wexford is still identified today. The tradition says that piling stones on it keeps her underground — and the stones need to be replaced.
Dobhar-Chú | Dobharachú
The water hound — half otter, half dog, entirely dangerous. It lived in Irish lakes and rivers and attacked without warning. Its hide was said to repel bullets. A gravestone in Co. Leitrim, dated 1722, appears to show one being hunted — making it one of the few creatures in Irish folklore with a datable physical record.
Dullahan | Dulachán
The headless horseman of Irish tradition — and far more terrifying than the American version. He rides a black horse and carries his own glowing head under one arm. When he stops and calls out a name, the person dies. He uses a human spine as a whip. The only thing that can drive him away is gold.
Far Darrig | Fear Dearg
The Red Man — a small fairy dressed entirely in red who specialised in horrifying practical jokes. He would arrive at night asking for shelter and then spend the hours until dawn putting his host through a string of nightmares and terrors. The polite response when he appeared was: ná dean magadh fúm — don’t mock me.
Fear Gorta | Fear Gorta
The Man of Hunger — a skeletal figure who wandered the roads begging for food. Giving to him brought luck; turning him away brought famine into your house. The Fear Gorta was part of Irish tradition long before the Great Famine of the 1840s — but the catastrophe of those years gave the legend a new and terrible weight.
Gancanagh | Gean Cánach
A fairy bachelor who wandered lonely places and seduced young women with nothing more than his presence and a clay pipe. Any woman who fell for him would waste away with longing after he left. His name means “love talker.” He never stayed.
Merrow | Murúch
The Irish merfolk — sea people who lived under the waves and came ashore out of curiosity. A Merrow woman could only stay on land if her magic cap was hidden from her; when she found it, she went back to the sea. Seeing a Merrow near the shore was a warning of storms coming.
Selkie | Rón Duine
A seal in the sea and a person on land. The Selkie shed its skin to take human form. Whoever found the sealskin and hid it could keep the Selkie on land. She might marry, raise children, build a whole life — but if she ever found her skin again, she went back to the sea. She always went.
Sluagh | An Slua Sí
The host of the unforgiven dead — souls condemned to fly in great flocks from the west, looking for the dying to carry off. People kept the windows on the west side of the house closed when someone lay near death. Of everything in Irish folklore, the Sluagh may be the most purely terrifying.
See also: Irish Gods | Irish Goddesses | Irish Heroes | Irish Myths & Stories