In Slavic mythology, a rusalka (plural: rusalki) is a female ghost, water nymph, succubus, or mermaid-like demon that dwelt in a waterway.
According to most traditions, the rusalki were fish-women, who lived at the bottom of rivers. In the middle of the night, they would walk out to the bank and dance in meadows. If they saw handsome men, they would fascinate them with songs and dancing, mesmerize them, then lead them away to the river floor to their death.
Though in some versions of the myth, their eyes shine like green fire, others describe them with extremely pale and translucent skin, and without visible pupils. The rusalka’s hair is sometimes depicted as green or golden, and often perpetually wet. The rusalka could not live long on dry land, but with her comb she was always safe, for it gave her the power to conjure water when she needed it. According to some legends, should the rusalka’s hair dry out, she would die.