Nakh

Shapeshifting water demons who appear most frequently as handsome men or beautiful women, the nakh, like the Greek Sirens, lure their victims into the river or sea with the sound of their sweet, seductive singing. Very often, according to old Estonian folklore, the spirits of the drowned may also become nakhs, seeking to entice the living into watery graves. Even if one should escape the enchantment of their singing, the very sighting of a nakh is a bad omen, usually a sign that either the witness or someone dear to him will die soon in river, lake, or ocean.

Sources: Larousse Dictionary of Worl Folklore. New York: Larousse, 1995.