The nuckelavee or nuckalavee is a horse-like demon from Orcadian folklore that combines equine and human elements. If one was looking casually, or under the cover of shadow in the night, it was though
The nuckelavee chasing an islander, painting by James Torrance (1859–1916).
The tempestuous seas of Orkney are home to the nuckelavee.
The nixie, nixy, nix, neck, or nicker, are humanoid, and often shapeshifting, water spirits in Germanic mythology and folklore.
Nuckelavee
…that appears as a horse-like demon when it ventures onto land. Writer and folklorist Ernest Marwick considered it very similar to the Norwegian nøkk, the nuggle of Shetland and the kelpie. A unique and solitary creature possessing extensive evil powers, its malevolent behaviour can influence events…
Nøkken by Norwegian artist Theodor Kittelsen, 1904
Strömkarlen ("The Stream Man") by Swedish painter Ernst Josephson, 1884. In Sweden, the Nixie is often romanticised as a fair naked man, playing music to lure people in.
"The Water Sprite" by Norwegian Theodor Kittelsen (1857–1914)
Näcken ("The Nixie") by Johan Tirén (1853–1911), featuring a young boy learning violin from The Nixie in the waterfall.