39 Intriguing Creatures & Monsters from Celtic Mythology

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Your guide to Celtic spirits, magical beasts, fairy folk & more

Co-authored by Jason Zuk and Amy Bobinger, BA

Last Updated: June 5, 2025 Fact Checked

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• Mythical Beasts
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• Vampires & Monsters
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• Tricksters
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• Spirits & Deities
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• Fairy Folk

|Show more |Show less

Celtic folklore is rich and colorful, full of a wide variety of interesting creatures. You’ll find familiar creatures like vampires and mermaids, prowling monsters, mischievous tricksters, and alluring fantasies that no doubt originated as cautionary tales. We’re taking a deep dive into the most interesting creatures from Celtic mythology—the harmless, the scary, and everything in between.

5 Popular Creatures from Celtic Mythology

• Leprechaun—Tricksters that have to grant you 3 wishes if you catch one
• Banshee—Wailing spirits that appear when someone is close to death
• Merrow—Irish mermaids known for luring men into the water
• Each-Uisge/Kelpies—Water horses that lure people into the water
• Aos Sí—Fairies, thought to be the descendants of an ancient race of gods

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Section 1 of 5:

Mythical Beasts

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   Cú Sidhe (Cù-sìth, Cŵn Annwn, Coinn Iotair)—Black Dog of the Fairies This supernatural dog of Celtic legend is said to have been the size of a small horse, with glowing red eyes. The fairies used them to hunt and kidnap human women to use as wetnurses for fairy babies, and the sight of them was said to be a sign that someone would die soon.

   • A church in the town of Blythburgh has a door with scratch marks that are said to have been left by the Cú Sidhe.
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   Cat-Sìth (Cat Sidhe)—Black Cat of the Fairies The Cat-Sìth was said to be a large black cat, about the size of a dog, with a white spot on its chest. In Scottish lore, it was believed that the Cat-Sìth would steal the soul of someone who died, so wakes often involved loud games and other rituals that would keep the cat distracted until the gods could properly claim the soul.

   • Some legends say that the Cat-Sìth only walks on all fours like a cat if humans are watching—otherwise, it walks on its hind legs.
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   Each-Uisge and Kelpies—Water Horses Each-Uisges and Kelpies are Celtic shapeshifters that most often appear as a horse, although they sometimes take the form of a bird or human. They live in water, and they lure people to the edge of the water, then pull them in and eat them.

   • The Each-Uisge lives in the sea or fresh-water lochs, while Kelpies live in rivers and streams.
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   Oilliphéisteanna—Great Wyrms of Ireland The Great Wyrms are Irish dragons, but they don’t have wings—the first Wyrm is said to have started off as a small, hairy worm that grew into a large creature that fed on cattle. Some people say that the worms inhabit lakes in Ireland, eating anyone who swims in the waters.

   • These legends persist today—there’s a story from 2003 that a sonar scan of a lake in Kerry found a giant fish that is said to have been the size of a two-story building—some people believe this creature, nicknamed “Muckie,” is a remnant of the Oilliphéisteanna.
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   Oilliphéist—Sea Dragon The Oilliphéist was a great, scaled serpent that lived in the waters of the River Shannon. It was said to be able to cause floods and other natural disasters, and was big enough to swallow whole ships.

   • The Oilliphéist had sharp claws and teeth, and it’s said that looking into its eyes could hypnotize a person.
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   Man-Wolves of Ossory (Werewolves of Ossory) According to legend, the descendants of prince Laignech Fáelad of Ossory were able to transform themselves into wolves. They would roam the countryside, feasting on both people and cattle.

   • It’s said that when the man-wolves were in wolf form, their human form remained behind, appearing as if it was dead.
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   Aillén Trechenn (Ellen Trechenn)—Three-Headed Monster The Aillén Trechenn is a monster that lived in a cave called Oweynagat near Cruachan. The monster would frequently terrorize the Irish capital Tara before finally being killed by the poet Amairgin.

   • The Aillén Trechenn is sometimes described as a male monster, and sometimes female.
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   Failinis (Fail Inis)—Dog of Lugh Lugh the Sun God sent three brothers on a quest to find the legendary dog Failinis as vengeance for killing Lugh’s father Cian. The dog was said to appear as a sheep by day, and any water that touched its fur would be transformed into wine or mead.

   • Failinis is sometimes depicted as belonging to the brothers—possibly when they’re on their way to deliver him to Lugh.
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   Glas Gaibhnenn (Glas Gainach)—The Green Cow of the Smith The Glas Gaibhnenn was a mythological cow that is said to have belonged to three brothers, including Goibhniu, the smith of the Tuatha Dé Danann. The Glas Gaibhnenn never ran out of milk and was said to be able to fill any container.

   • The cow was eventually stolen by Balor, god of the Fomorians.
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Section 2 of 5:

Vampires & Monsters

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   Abhartach the Dwarf Vampire King Abhartach is an Irish vampire legend that first appears in The Origins and History of Irish Names of Places, an 1870 book by Patrick Weston Joyce. Abhartach was a tiny, cruel tyrant who ruled over the town of Errigal. Even after being killed and buried, he came back to torment the people of Errigal again—some legends say he drank blood after he returned.

   • Abhartach was finally defeated when he was killed and buried standing upside-down, and a large stone or grove of yew trees were placed over his grave.
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   Dearg Due—The Red Thirst The Dearg Due was originally a young woman who was forced by her father to marry a wealthy man she didn’t love. She died soon afterward and returned from the grave for vengeance. First, she killed her father, then she killed her evil husband and drank his blood.

   • After she took her vengeance, she developed a vampiric thirst for blood, and was rumored to lure unsuspecting young men into the dark, where she would drink their blood.
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   Fomorians—Ancient Monsters The Fomorians were an ancient race of monsters from under the sea who terrorized the people of Ireland each year on Samhain. They were said to be ugly and deformed, with great magical powers.

   • Eventually, the Fomorians were driven out of Ireland after their king Balor was killed by the Tuatha Dé Danann.
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   Balor of the Evil Eye (Balór na Súile Nimhe) Balor is a one-eyed monster, and legend says that anyone who looked into his eye would be destroyed. He was the leader of the Fomorians, and he eventually led the battle against the Tuatha Dé Danann, where he was killed.

   • Balor is the grandfather of Lugh the Sun God and the great-grandfather of legendary Irish warrior Cú Chulainn.
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   Buggane—The Ogre The Buggane was a giant ogre who lived in forests, waterfalls, and mountains—remote places, as they didn’t like to be disturbed. They were said to shape-shift, but in their natural form, they had glowing eyes, cloven feet, and were covered with thick hair.

   • One legend says that the church of St. Trinian’s was being built too close to a Buggane’s lair, so the Buggane tore the roof off the church each time it was built—the church couldn’t be completed until the Buggane died.
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   Nuckelavee—Devil of the Sea Although it primarily lived in the sea off of Northern Scotland, the Nuckelavee sometimes appeared on land, bringing fear and death with it. This creature had legs like a horse and the torso of a man, with arms that were long enough to reach the ground. It didn’t have skin or hair, and its breath could kill crops.

   • The Nuckalevee only appeared during winter and couldn’t cross fresh water.
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Section 3 of 5:

Tricksters

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   Leprechaun—The Trickster The Leprechaun may be the most well-known figure from Celtic mythology. This tiny trickster is usually depicted as dressing in green, and he prefers to keep to himself, often spending his time making shoes and guarding their gold.

   • Legend says that if you can capture a leprechaun, he’ll have to grant you three wishes—but these crafty little creatures aren’t easy to catch!
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   Clurichaun (Cluracaun)—Wine Drinkers Clurichauns are similar to the better-known Leprechaun—they’re both small, mischievous sprites or goblins. But where leprechauns are shy and solitary, clurichauns are found in wine cellars, where they drink all the wine they can find.

   • Some legends say that clurichauns and leprechauns are the same creature.
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   Far Darrig (Red Man, Rat Boys)—The Far Darrig is usually depicted either as dressing in red or as having bright red hair. It’s a small creature, similar to a leprechaun, and this shape-shifter is renowned for playing tricks on people. The Far Darrig can appear anywhere, but it’s especially known to show up around households and farms.

   • Some legends portray the Far Darrig as being vengeful or spiteful, but others show it as being a fun-loving spirit who plays harmless pranks.
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   Boggart—Mischievous Spirits Boggarts are tricksters who would play pranks in people’s homes, like rearranging the furniture or breaking dishes while they slept. But Boggarts weren’t always evil—if they were treated well, they would be helpers in the household, only causing mischief if they were insulted.

   • Families often left out offerings for Boggarts to keep on their good side.
   • In some places, the term “Boggart” refers to any spirit that scares people.
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Section 4 of 5:

Spirits & Deities

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   Banshee (Hag of the Mist, Bean-nighe) The Banshee is one of the most famous figures in Celtic mythology. They’re often attached to a particular family, appearing with wails and shrieks when someone in the family is near death. Many legends say that banshees wash the burial clothes or death shroud of the person who’s going to die, giving them the nickname “washerwomen.”

   • Some see banshees as remnants of the Tuatha Dé Danann, while others believe they’re the ghosts of departed family members.
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   The Merrow—Irish Mermaids The Merrow were sea creatures who looked like a beautiful maiden from the waist up, but from the waist down they had long, shimmering fish tails. They were said to sing enchanting songs that would lure men to the water, where they would drown.

   • The Merrow were capable of taking on human form, even marrying and living on land, but their heart always belonged to the sea.
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   Dullahan—Headless Horseman The Dullahan is a fearsome creature that’s said to ride a black horse, carrying his head under one arm. His face has the pale color of old dough and a wide, evil grin, and in his other hand, he carries a whip made of a human spine. He rides through the night, and when he stops his horse, he calls out the name of a person who is about to die.

   • Some legends say that he drives a carriage drawn by headless horses.
   • The Dullahan may have inspired Washington Irving’s story “The Legend of Sleepy Hollow.”
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   Ankou (Ankow, Angau) The Ankou is a Grim Reaper figure—a tall, thin man dressed in black, wearing a wide-brimmed hat and carrying a scythe. Sometimes he rides in a coach and other times he pulls a wheelbarrow, and seeing him means that death is near.

   • Some legends say that each town has its own Ankou—the last person to die each year.
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   Fear Gorta—The Hungry Man The Fear Gorta is reputed to walk the land, knocking on people’s door and asking for food. If the person feeds the Fear Gorta, he would sometimes reward them generously, but if they refuse, he would curse them with bad fortune and hunger.

   • The Fear Gorta is portrayed as a man with dirty nails and greenish skin, carrying a bowl that he is barely strong enough to lift.
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   The Cailleach—The Midwife, The Old Woman, The Queen of Winter The Cailleach is an old woman with pale or blue skin and red teeth who often wears a veil. She sometimes only has one eye. Legend says that she could ride storms and leap over mountains. She’s not really considered good or evil—she represents the powerful forces of nature and the destruction they could bring, but she also protected animals during the winter.

   • Each year, as winter turned to spring, the Cailleach would become youthful, aging into a hag again as winter approached.
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   The Bodach—The Poor Farmer The Bodach often appears in the worn clothes of a farmer or peasant, and he’s thought to be the husband of the Cailleach. He’s a trickster who’s said to annoy people to keep them awake, and the sight of him could signify death.

   • The Bodach is also known as the King of Mag Mell, a mythical island off the coast of Ireland where the living can enjoy a life free of sickness, hunger, or aging.
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   Bananach (Na Bánánaigh)—Warrior Demons The Bananachs were goatlike air spirits that could be found flying above fierce battles, shrieking and dancing as they celebrated the fight. After the battles, these monstrous creatures would drink the blood of those who were killed.

   • Some legends say that the Bananach were originally summoned by the Tuatha Dé Danann, but that once they were called, they didn’t leave.
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   The Morrígan—Goddess of War and Death The Morrígan often appeared to prophesy for warriors and gods, and the sight of her often foretold death. She sometimes appeared as a beautiful woman, using her wiles to charm and influence kings and other powerful men. Other times, she appeared as a raven, circling above battlefields waiting to carry off the fallen for food.

   • The Morrigan is sometimes depicted as an individual and sometimes as a trio of goddesses—Badb, Macha, and Nemain.
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    Sluagh—Soul Stealers The Sluagh were rumored to wander the earth on Samhain, looking for souls to add to their numbers. They sometimes appeared as a flock of ravens, their wings appearing as smoke, and often appear when someone is near death, hoping to steal their soul.

    • Some people believe the Sluagh are fairies, while others think they’re the spirits of people who weren’t accepted into the afterlife.
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Section 5 of 5:

Fairy Folk

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   Aos Sí (Sidhe, Aes Síde)—The Fairy People Descended from an ancient race of gods known as the Tuatha Dé Danann, the Aos Sí are the legendary fairies of Celtic mythology. They’re said to live underground, across the sea, or in an invisible world. They’re protective guardians of nature, and they’re known to curse anyone who crosses them.

   • People often left offerings of milk, baked goods, and berries as treats for the fairies and to earn their goodwill.
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   Alp-Luachra (Art-Luachra, Airc-Luachra)—Joint-Eater The Alp-Luachra is a type of fairy that lives in freshwater. Legend says that if you fall asleep near a river or stream, the invisible Alp-Luachra may slither into your throat. Once it’s there, the Alp-Luachra will eat the best part of every meal you eat—gradually causing you to waste away.

   • According to legend, if you eat a great deal of salty food then lie down by fresh water with your mouth open, the thirsty Alp-Luachra will eventually crawl back into the water and swim away.
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   Aibell (Aoibhell, Aoibheall)—Fairy Queen of Love Aibell, or the Fairy Queen, carried a shimmering harp made of gold, and according to legend, her music was so beautiful that anyone who heard it would soon die. She held a midnight court in County Clare, and any husbands who were found to mistreat their wives were sentenced to being plagued by fairies.

   • Legend says that you can still see Aibell dancing in the moonlight near County Clare.
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   Gancanagh—The Love Talker The Gancanagh is a tall fairy who’s known for enchanting and luring young women. After seducing the women with his charm and promises of love, he moves on, leaving them to deal with a broken heart.

   • The Gancanagh is often pictured in stylish clothing with a dudeen, or pipe.
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   Leannán Sidhe—Fairy Lover Once part of the Tuatha Dé Danann, the Leannán Sidhe wanders in search of young men who are artists, musicians, or writers. Although she doesn’t have a face of her own, when the men see her, she takes on the form of a beautiful woman, and they become obsessed with her, eventually wasting away as they search for her again.

   • Legend says that the Leannán Sidhe then brings these men to the underworld to create art for her.
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   The Púca (Pooka)—Fairy Goblin The Púca were shape-shifting fairies that took the form of various jet-black animals. Typically residing in rural areas, the Púca were usually known for causing mischief, although there are tales where they would attempt to stop a disaster or accident from happening.

   • According to legend, the Púca would often take the form of a horse, then pick up someone who’d had too much to drink and take them on a wild ride.
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   Amadan Dubh (Amadan Briona)—the Black Fool According to legend, Amadan Dubh is a powerful fairy who served as jester to Aibell’s midnight court. He played a reed pipe to lure people near him, and if he touched someone, they would become paralyzed.https://emeraldisle.ie/amadan-dubh

   • Amadan Dubh’s touch was known as the Gaoth Sidhe, or fairy wind.
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   Abcan (Abhcan) Mac Bicelmois—The Harper of Tuatha Dé Danann Abcan is described as a little man who wore magical purple clothing—it’s said that his clothing would protect anyone who wore it, would fit them no matter their size, and would become whatever color the wearer wished. He also had a bronze boat with a tin sail, which he used to carry people back and forth from the underworld.

   • Abcan is also known as Senbecc in some legends.
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   Manannán Mac Lir—The Sea God Manannán Mac Lir was one of the Tuatha Dé Danann, and he ruled over the sea. He was said to have been able to travel to the otherworld through mists and was a master of illusions.

   • Legend says that Manannán had a magical horse called Aonbarr that could travel over water like it was land.
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    Changeling—Stolen Child Fairies were rumored to steal children, and they’d leave a replacement in its stead—a changeling, often an elderly fairy who wanted to be cared for by humans until it died. The changeling would look like the child, but it might act in an unusual way, take on a slightly different appearance, or be unable to move its limbs.

    • Unfortunately, this myth was often used to explain children who were struck by various illnesses or conditions, and people would abandon these children, thinking them to be fairies.
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