kelpie
Scottish Gaelic cailpeach or colpach "heifer, colt"
The horse's appearance is strong, powerful, and breathtaking. Its hide was supposed to be black (though in some stories it was white), and will appear to be a lost pony, but can be identified by its constantly dripping mane. Its skin is like that of a seal, smooth but is as cold as death when touched. Water horses are known to transform into beautiful women to lure men into their traps. It is understood that the nostril of the horse is what creates the illusion of grandeur. The water horse creates illusions to keep itself hidden, keeping only its eye above water to scout the surface, much like the illusion of a fish's pupil. It is wise to keep away from them.
The fable of the kelpie differs depending on the region where it is told. Other versions of the story describe the kelpie as "green as glass with a black mane and tail that curves over its back like a wheel" or that, even in human form, they are always dripping wet and/or have water weeds in their hair.
The water horse is a common form of the kelpie, said to lure humans, especially children, into the water to drown and eat them. It performs this act by encouraging children to ride on its back. Once its victims fall into its trap, the kelpie's skin becomes adhesive and it bears them into the river, dragging them to the bottom of the water and devouring them-except the heart or liver.
On the Isle of Man it is known as the cabbyl-ushtey (Manx Gaelic for "water horse", compare to Irish capall uisge) or the glashtin. In Wales, a similar creature is known as the Ceffyl Dwr.