Elementals who cohabit with human males and may even enter into marriage relationships with them. The children of such unions receive souls from their human fathers and so are to be considered human beings. The Undine is a kind of Water Nymph, derived from many related water goddesses. She is beautiful, stirs great lust in men, and is renowned for her possessiveness and jealousy. If her human lover or husband should be unfaithful to her even once, she will disappear and he will never see her again.