Kelpie

A Kelpie is a shapeshifting water demon native to Britain and Ireland. Able to take any form, they usually take the form of a horse with a bullrush mane. After luring unwary travellers onto their backs, they drag them underwater and eat them, allowing the entrails to float to the surface of the water. A Kelpie can be rendered docile and harmless by using a Placement Charm to put a bridle over the creature's head.

Kelpie hair can be used as a wand core, although it is said to be an inferior substance when compared with Unicorn hair, Phoenix feather and Dragon heartstring.

Known Kelpies

 * The largest reported Kelpie is the Loch Ness Monster, who resides in Loch Ness, Scotland. Its favourite form is that of a sea serpent which leads to many Muggle sightings.

Harry Potter's experiences

 * In Harry Potter's second year, Gilderoy Lockhart gave Rubeus Hagrid unsolicited advice about getting kelpies out of a well, which Hagrid found irritating.
 * In Harry's sixth year, when Harry and Albus Dumbledore had to cross the black lake in the Horcrux cave, Harry's thought that the lake might hold kelpies, as well as other aquatic beasts such as water monsters, giant serpents, demons and sprites.

Appearances

 * Harry Potter and the Chamber of Secrets
 * Harry Potter and the Half-Blood Prince
 * Fantastic Beasts and Where to Find Them
 * Harry Potter: Trading Card Game
 * Pottermore
 * Wonderbook: Book of Spells