Each-Uisge

While the kelpie haunts rivers, the Each-Uisge ('water horse') haunts the deep sea-lochs and mountain lakes of the Scottish Highlands. It was considered more dangerous than the kelpie because it would carry its victim into the loch and devour all but the liver, which would wash ashore. Like the kelpie it shapeshifted between horse and human form, but it was known to take the form of a handsome young man to lure women specifically.

A horse of unusual beauty and apparent tameness found near lochs, with a hide that is always damp. In human form, a handsome young man whose hair has the texture of wet seaweed. In horse form its mane drips perpetually.

Adhesive hide that stuck to riders. Extreme speed into and through water. Could take human form to lure victims differently from horse form. Consumed victims entirely underwater, leaving only the liver.