The Celtic shapeshifting creature that often appears as a horse or goat is the púca.
The púca is a supernatural being of Irish and wider Celtic folklore, regarded in different traditions as a trickster, spirit, goblin, or fairy creature. Its name has related forms, including pwca in Welsh, bucca in Cornish, and pouque in Channel Islands folklore. These parallels reflect a broad northwestern European family of supernatural beings rather than one single standardized myth.
A púca can assume many forms. Common appearances include a dark horse, goat, cat, dog, hare, raven, fox, or wolf, and it may also take human form while retaining animal features such as ears or a tail. Stories often emphasize its ability to confuse, frighten, or lead travelers astray.
The púca is frequently confused with the kelpie or each uisge because all can appear as horses. In Irish lore, however, the púca is not consistently a water-dwelling killer. Some tales portray it as mischievous but ultimately helpful, and it is sometimes said to speak, offer advice, or guide people away from danger.