Grindilow

Creatures from folklore The British Isles. These are aggressive mermaids-aquatic, living in flowing waters. 

Small creatures of green, grayish or "swamp-green" color, which helps them to merge with swamp or lake water, because they live in such overgrown with algae, gloomy lakes or swamps, of course – there is no better place to find. Grindilow's "faces" are quite ugly, the head is crowned with a pair of sharp horns, which, if desired, can make a person or just an enemy very painful. In addition, they have very sharp fangs, and long thin fingers end in the same long sharp yellow claws.

They are quite curious, and it is impossible to say for sure whether grindilows are smart or not, but when it comes to something bad, they have a lot of ingenuity. For example, they are able to sneak up on someone who got lost in a swamp, or swim up to a person in a lake and drag him under water.

In Lancashire, the same evil is known as Green-Toothed Jenny. In other parts of England she is known as Long-Armed Nelly. A relative of grindilow is also the Well Peg, which lives in wells.