Kelpie

General about Kelpie
The Kelpie is a mythical creature, that has his origin in Scotland. It's a shape-shifting creature, which lives in the water and shape-shifts into different forms, for example in a handsome man. The most known Kelpie is the Monster of Loch Ness. In that case, there is the theory, that it hasn't been found, because it just shape-shifts in the form of an otter or a fish. Transfigured Kelpies are usually associated with old, shaggy men or handsome young man, but traditionally, there all male. There are a few stories about female Kelpies dressed in long green dresses, but those are really rare.

Legends
“…When thowes dissolve the snawy hoord An’ float the jinglin’ icy boord

Then, water-kelpies haunt the foord

By your direction

And ‘nighted trav’llers are allur’d

To their destruction…”

Origin of this Legend
The first thing that makes the Kelpies so famous is The Monster of Loch Ness or short "Nessie". It is apparently a Kelpie and the fake photograph from 1943 makes it even more famous. Also, it's a really common story about the horse, that can walk on water or swim in water. The origin could be, same as the Ceffyl Dŵr, when a person didn't come back from the lakes, the people would be scared what happened to him. When they then saw a horse or even a person that they never saw before, they would make up stories about those and it would all merge together to one big stories. Also, in general with stories like this, they e´were made to keep the kids away from the waters, cause in most cases, they couldn't swim.