The Nøkken is a male water spirit of the Nordic lakes and streams who plays enchanted songs to lure people to drown. He appears as a man playing the violin in brooks and waterfalls, or in animal form — most commonly as a "brook horse."
His music was most dangerous to women and children, especially pregnant women and unbaptised children. Shapeshifting was thought to be one of his central attributes; perhaps he had no true shape at all. He is kin to the Danish nøkke and the Swedish näck.