The nix, or as we call him in swedish folklore "Näcken" is an evil water spirit, living in the forest. He can take the shape of an naked man, playing seductive melodies on he's violin fooling his victim down in the the water and then drowns them. He can also take the shape of an white horse that fools you to ride on he's back. The back can grow longer to make more room for more people, and then he will drown them. So if you here the violin playing in the woods, you better run.
faceup and body blush by me.