Sixteen of them, from the woman whose cry means a death in the family to a monster with its own gravestone. Most were written down only in the 1800s, a few go back to the medieval manuscripts, and each one below says which.
A warning about the other lists. Most of them are "Celtic" lists, and they mix Irish, Scottish and Welsh folklore as if it were one thing. The kelpie, the selkie and the washer at the ford turn up as Irish all the time. They are Scottish, and they are at the bottom of this page with the reason.
bean sí · woman of the fairy mound
A woman whose cry tells a family that one of them is about to die. She is heard more than seen: a keening at night, sometimes a woman combing her long hair. The name ties her to the síde, the ancient mounds that dot the country, and her wail echoes the real keening woman, the bean chaointe, who lamented the dead at Irish funerals.
púca · spirit, ghost
A shape-changer that brings good luck or bad, and could take the form of a horse, a goat, a cat, a dog or a hare, or a person with an animal's ears or tail. The dark horse is the form most told.
leipreachán, luchorpán
A small solitary fairy, a shoemaker in the folklore, fond of practical jokes. The earliest mention is medieval: in the tale of Fergus mac Léti, a king of Ulster falls asleep on the beach and wakes to find three lúchorpáin dragging him into the sea.
clúrachán
A solitary fairy who haunts cellars, breweries and pubs and loves drink. He is so like the leprechaun that folklorists disagree whether he is a separate creature, a regional name for the same one, or, as some put it, a leprechaun on a spree.
fear dearg · red man
A small fairy in a red coat and cap, given to practical jokes, and in the older descriptions to gruesome ones. An 1832 account from Munster puts him at about two and a half feet tall, wrinkled, with long grey hair and a sugarloaf hat.
dúlachán
A headless rider on a black horse, or the driver of a coach, carrying his own head.
murúch · sea maid
The Irish mermaid, who needs a magic cap, the cochaillín draíochta, to pass between the sea and the land. In the Kerry story of the Lady of Gollerus a local man takes her red cap and marries her.
A fairy left in place of a stolen child, and in Ireland sometimes of a stolen adult. The belief is found across Europe; Ireland is one of the places where adults were said to be taken too.
gean cánach · love talker
A male fairy who seduces women, and whose name says how: he talks them into it.
aos sí · people of the mounds
Not one creature but the fairy race itself, the people who live inside the síde, the mounds that are doorways to the Otherworld. They are said to descend from the Tuatha Dé Danann, the old gods, who went into the mounds when they lost Ireland.
slua · host, crowd
The host of the unforgiven dead, flying through the air in a flock like birds and carrying people off. Mostly dangerous to the living.
dobharchú · water hound
The king otter, half dog and half otter, living in lakes. It has something no other creature here has: a gravestone. In Conwall cemetery in Glenade, County Leitrim, a headstone carved with the animal is said to mark a woman killed by one at Glenade Lough in 1722.
ollphéist · great beast
The Irish dragon or water serpent. One story has an ollphéist fleeing St Patrick and carving the course of the River Shannon as it goes; another, the Caoránach, is killed or banished by him in Lough Derg in Donegal, whose red rocks are said to be stained with its blood.
The people of Osraige, the old kingdom around Kilkenny, were said in medieval Irish, Norse and English writing to be able to turn into wolves. Gerald of Wales tells of a priest travelling from Ulster to Meath who meets a wolf in the woods.
Fomóire
The monstrous race of the Mythological Cycle, from under the sea or the earth, enemies of Ireland's first settlers and of the Tuatha Dé Danann, who defeat them at the second battle of Mag Tuired. Balor of the evil eye was one.
abhartach · dwarf
A malevolent dwarf who rose from his grave, first written down by P. W. Joyce in 1870. The story looks a great deal like later vampire stories.
The best known are the bean sí (banshee), the púca, the leprechaun, the dullahan, the merrow and the changeling. Behind them all are the aos sí, the fairy people of the mounds. The monstrous Fomorians and the werewolves of Ossory come from the medieval literature; most of the others are folklore that was only written down in the 19th century.
No. The kelpie is from Scottish folklore. Ireland has water-horse stories of its own, the each uisce, but the kelpie is Scottish, as are the selkie and the bean-nighe, which are often put on lists of Irish creatures.
None: banshee is the English spelling of bean sí, woman of the fairy mound. She is a spirit whose cry warns a family that one of them is going to die.
The name is old. Lúchorpáin appear in the medieval tale of Fergus mac Léti, dragging a king of Ulster into the sea. But the leprechaun rarely appears in Irish mythology, and the shoemaker with the pot of gold, and especially the green suit, belong to much later folklore and to the 19th and 20th centuries.
The usual answers are the dullahan, the headless rider, and the sluagh, the flying host of the dead who carry off the living. The changeling is the darkest in fact rather than in story, because people believed to be changelings were sometimes harmed.
For the real stories, collected from people's grandparents in the 1930s, the Schools' Folklore Collection at Dúchas ↗ is free to read, county by county.
The four cycles of Irish mythology · The gods and goddesses they came from · What people did about them: Irish superstitions · The Tuatha Dé Danann and the Fomorians · Samhain and the old year