Kelpie

Kelpies are malevolent, amphibious fey shapechangers who lure mortals to a watery grave. These cruel predators lurk around bodies of water of any type, only slightly preferring fresh water over salt water. Kelpies lure or drag their prey underwater, then drown and devour them, leaving behind only the victim's heart and liver—the only parts of a meal kelpies find unpleasant—tossed upon the shore. Kelpies are fond of magically disguising themselves as fine steeds or attractive strangers to draw in victims, but their true appearance is that of a hideous equine with slimy, green flesh resembling aquatic plants.