The púca (Irish for spirit/ghost) is primarily a creature of Irish folklore. Considered to be bringers both of good and bad fortune, they could either help or hinder rural and marine communities. The creatures were said to be shape changers which could take the appearance of black horses, goats and rabbits #folklore
In Welsh mythology and folklore, Cŵn Annwn were the spectral hounds of Annwn, the otherworld of Welsh myth. They were associated with a form of the Wild Hunt, presided over by Arawn, king of Annwn. They are often depicted as white with red ears.
"Daughter of the Sea". Selkies are mythological creatures found in Faroese, Icelandic, Irish, and Scottish folklore. They are said to live as seals in the sea but shed their skin to become human on land. The legend apparently originated on the Orkney and Shetland Islands and is very similar to those of swan maidens.
The maiden fetched the magic wand, and then she took her stepsister’s head and dropped three drops of blood from it. Illustration by Arthur Rackham for Sweetheart Roland, a fairy tale by the Brothers Grimm
The Mabinogion is the title given to a collection of eleven prose stories collated from medieval Welsh manuscripts. The tales draw on pre-Christian Celtic mythology, international folktale motifs, and early medieval historical traditions. While some details may hark back to older Iron Age traditions, each of these tales is the product of a highly developed medieval Welsh narrative tradition, both oral and written.