lilymoth:

Legendary Creatures: Rusalki 

Rusalki are fish-women, who lived at the bottom of rivers. In the middle of the night, they walk out onto the bank and dance in meadows. If they saw a handsome man, they would fascinate them with songs and dancing, mesmerize them, and then lead them away to the river floor to their death. 

In Slavic lore especially, rusalka are “the spirits of girls who died ‘before their time’ and returned to live as spirit being in our world, near where they had once lived and died” [x]