This list of mythical creatures that begin with this letter and I am constantly gathering information from each continent, and is continually being updated.
Kelpie (Irish and Scottish)
A kelpie, or water kelpie, is a shape-shifting spirit inhabiting lochs in Irish and Scottish folklore. It is usually described as a black horse-like creature, able to adopt human form. Some accounts state that the kelpie retains its hooves when appearing as a human, leading to its association with the Christian idea of Satan as alluded to by Robert Burns in his 1786 poem "Address to the Devil".
A kelpie is a shape-changing aquatic spirit of Scottish legend. Its name may derive from the Scottish Gaelic words ‘cailpeach’ or ‘colpach’, meaning heifer or colt. Kelpies are said to haunt rivers and streams, usually in the shape of a horse. These water horses can also appear in human form. They may materialize as a beautiful young woman, hoping to lure young men to their death. Or they might take on the form of a hairy human lurking by the river, ready to jump out at unsuspecting travellers and crush them to death in a vice-like grip.