This is the “devil of the sea”.
Its disfigured half human, half horse body is feared.
It is considered a malevolent being who kills crops and livestock with its breath.

[*] A Nuckelavee is a demonic sea creature in Scottish and Norse mythology.
It is described as looking like a horse with a human rider fused to it.
The human arms are so long they can reach the ground.

James Torrance
Its head is three feet around and it has sometimes been reported to have two heads.
[*] The Nuckelavee has no skin.
Black blood is visible circulating through its veins.

A Kelpie, by Herbert James Draper
[*] The prefix nuck may be derived from the word for the devil.
The name as a whole means devil of the sea.
[*] Both the Kelpie and the Nuckelavee are malevolent, possibly Satanic.

Nuckelavee habitat, by Colin Park
[*] There are no good qualities attributed to the Nuckelavee.
They are a product of Orcadian and Norse mythology and are not considered real.