Nuckelavee

The nuckelavee ( /nʌklɑːˈviː/) or nuckalavee is a horse-like demon from Orcadian folklore that combines equine and human elements. It resembles a fleshless human head, torso, and arms longer than normal coming out of a fleshless horse's back at the point where a horse rider would usually sit as the horse body also sports one eye and fins on its legs. British folklorist Katharine Briggs called it "the nastiest" of all the demons of Scotland's Northern Isles. The nuckelavee's breath was thought to wilt crops and sicken livestock and the creature was held responsible for droughts and epidemics on land despite being predominantly a sea-dweller.

A graphic description of the nuckelavee as it appears on land was given by an islander who claimed to have had a confrontation with it, but accounts describing the details of the creature's appearance are inconsistent. In common with many other sea monsters, it is unable to tolerate fresh water. Therefore, those it is pursuing have only to cross a river or stream to be rid of it. The nuckelavee is kept in confinement during the summer months by the Mither o' the Sea, an ancient Orcadian spirit, and the only one able to control it.

Orcadian folklore had a strong Scandinavian influence, and it may be that the nuckelavee is a composite of a water horse from Celtic mythology and a creature imported by the Norsemen. As with similar malevolent entities such as the kelpie, it possibly offered an explanation for incidents that islanders in ancient times could not otherwise understand.