Cait Sith is an enemy from Final Fantasy IV.
Cat sìth (meaning "faerie cat", pronounced "Kat Shee") is a fairy creature from Celtic mythology, said to resemble a large black cat with a white spot on its breast. 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.