The cat-sìth (, plural cait-shìth), in Irish cat sí () is a fairy creature from Celtic mythology, said to resemble a large black cat with a white spot on its chest. Legend has it that the spectral cat haunts the Scottish Highlands. The legends surrounding this creature are more common in Scottish folklore, but a few occur in Irish. Some common folklore suggested that the "cat-sìth" was not a fairy, but a witch that could transform into a cat nine times.