An early Germanic Water Spirit
The Germans-like many other peoples-considered the spirits of water to be feminine. Like the rivers they inhabited, the Nixies were changeable in nature:sometimes charming and peaceful, sitting in the sun to comb their long blonde hair; sometimes fierce and hungry, drowning people for food.
The could assume human form to go to market or dance on the riverside; in this form, they were long-breasted young women about four feet tall, who might pass for completlely human except for the wet hems of their skirts and aprons. Mortal men often fell in love with them, wasting away because of their beauty; sometimes a Nixie could agree to marry a human, makng him vow never to ask her origin. When a Nixie died the river where she lived would run red with her blood.