Some of the Celtic creatures from tales are pretty badass.
Selkies live as seals in the sea but shed their skin to become human on land. They are mythological creatures found in Faroese, Icelandic, Irish, and Scottish folklore. Stories concerning selkies are generally romantic tragedies. Sometimes the human will not know that their lover is a selkie, and wakes to find them gone. In other stories the human will hide the selkie's skin, thus preventing it from returning to its seal form. A selkie can only make contact with one human for a short amount of time before they must return to the sea. They are not able to make contact with that human again for seven years, unless the human is to steal their selkie's skin and hide it or burn it. I read a book once about a selkie's daughter who found her mother's old skin and returned to the sea with it. It included other elements of the lore like selkie tears and blood causing storms and calling creatures from the sea.
The salmon of knowledge
The Salmon of Knowledge (Irish: bradán feasa) was sometimes called Fintan (or Finntan) in ancient times. An ordinary salmon ate nine hazelnuts that fell into the Well of Wisdom (aka Tobar Segais) from nine hazel trees that surrounded the well. By this act, the salmon gained all the world's knowledge. Moreover, the first person to eat of its flesh would, in turn, gain this knowledge. The story of Fionn MacCumhaill who caught the salmon and gained all its knowledge.
Gancanagh
A Gancanagh (from Irish: Gean Cánach meaning "love talker") is a male faerie in Irish mythology that is known for seducing human women. The Gancanagh are thought to have an addictive toxin in their skin that make the humans they seduce literally addicted to them. The women seduced by this type of faerie typically die from the withdrawal, pining away for the Ganacanagh's love or fighting to the death for his love. The faerie is typically depicted carrying a clay pipe, though he does not smoke it because faeries generally detest smoke.
Kelpie
The kelpie is a supernatural water horse that is believed to haunt the rivers and lochs; the name may be from Scottish Gaelic cailpeach or colpach "heifer, colt". Kelpies were said to transform into beautiful women to lure men into their traps. They created illusions to keep themselves hidden, keeping only their eyes above water to scout the surface. The water horse is a common form of the kelpie, said to lure humans, especially children, into the water to drown and eat them. The water horse would encourage children to ride on its back, and once its victims fell into its trap, the water horse's skin would become adhesive and the horse would bear the children into the river, dragging them to the bottom of the water and devouring them.
Banshee/ Bean Nighe
The bean nighe (Scottish Gaelic for "washer woman"), is a Scottish fairy, seen as an omen of death and a messenger from the Otherworld. She is a type of bean sìth (in Irish bean sídhe, anglicized as "banshee"). As the "Washer at the Ford" she wanders near deserted streams where she washes the blood from the grave-clothes of those who are about to die. It is said that mnathan nighe (the plural of bean nighe) are the spirits of women who died giving birth and are doomed to do this work until the day their lives would have normally ended. A bean nighe is described in some tales as having one nostril, one big protruding tooth, webbed feet and long-hanging breasts, and to be dressed in green.
Abhartach
Abhartach (also avartagh, Irish for dwarf) is an early Irish legend. This dwarf was a magician, and a dreadful tyrant, who when slain would rise again from the dead. Some think when he rose he drank his subjects' blood, and as a result was though of as an origin for the story of Dracula. Eventually a chief killed him and then consulted a druid, and according to his directions, and buried him with his head downwards; which subdued his magical power, so that he never again appeared on earth.
Source: http://imgur.com/gallery/iIzFC
source: https://33.media.tumblr.com/7c6d860cf0d2a85954e91d58460ff54f/tumblr_nciqvjGR3d1rvu01lo1_500.jpg
