The Cat Sìth — the 'fairy cat' — is a creature of Scottish Highland and Gaelic folklore, a large black cat the size of a dog with a single white spot upon its breast, seen slipping through the night with its back arched and fur bristling. Some held it to be a fairy; others believed it was a witch who could take cat-form nine times, but who would be trapped in the shape forever if she changed a ninth time.
The story
The Cat Sìth was most feared around death. It was believed that the fairy cat would try to steal the soul of a corpse before it was buried, by passing over the body, and so the Highlanders kept the 'Late Wake' or Fèill Fhadalach — watching the dead night and day, distracting the cat with games, riddles and music, and keeping no fire in the room, since warmth was thought to draw it. At Samhain a saucer of milk left out would win a household the Cat Sìth's blessing, while those who offered none would find their cows dry. The creature is often linked to the King of the Cats tales told across the Highlands.