A Fuath (pronounced foo-ah) (Fuathan pl.) is an evil, Gaelic water spirit.
The Scottish use the name 'Fuath' to refer to generic water spirits who inhabit the sea, rivers, fresh water, or sea loches like the Kelpie or Uisges in Northern Ireland or the Bean-Nighe. Sometimes, this name is even given to highland or nature spirits, but all forms with the name are evil.
Their appearance ranges from covered in shaggy, yellow fur to just having a mane down its back, webbed toes, tails with spikes, and no nose. Fuathan usually have green clothes, the color of fairies.
Fuathan sometimes intermarry with humans (typically the female), whose offspring will share a mane, tail, and/or webbed digits. Their banes include sunlight and cold steel, which will kill them instantly. They also grow restless upon crossing a stream.