This list of mythical creatures that begin with this letter and I am constantly gathering information from each continent, and is continually being updated.
Nuckelavee (Scottish)
The nuckelavee or nuckalavee is a horse-like demon from Orcadian folklore that combines equine and human elements. 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. 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.
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.