Rusalka

According to Slavic folklore, a Rusalka is something between an evil demon and a water nymph that only comes in a female form. It is believed that they live at the bottom of rivers (or lakes in rare cases) which is why some people falsely considered them to be mermaids. Rusalkas, however, are not mermaids but the spirits of dead women, usually of ones who have committed suicide over an unsuccessful love affair and are now after the whole of mankind seeking revenge. For that reason, they come out during the night and sing with beautiful and deceptive voices paired with entrancing and seductive dancing in order to seduce men to their watery grave.