Kelpie

The kelpie is one of the most well-documented supernatural beings in Scottish Highland folklore, with records from the 17th century onward. It haunted rivers and lochs in horse form, its hide perpetually damp. Children who stroked it found their hands stuck fast and were dragged into the water. Adults who mounted it could not dismount. One common tale involves a group of children — all but one stuck fast — being dragged under while the last child escaped by cutting off his own finger.

Usually appears as a beautiful, well-proportioned horse with a perpetually wet mane and hide that smells of the river. It may also appear as a handsome young man with weeds in his hair, identifiable if you can spot the tell-tale water-weed. Its mane is perpetually dripping.

Could make a rider or toucher stick fast to its hide. Immense strength in water. Shape-shifted between horse and human form. Could transform into a human to seduce victims to the waterside. Skin supernaturally adhesive.