Huldra
Huldra is a mysterious creature associated with hundlers and part of the troll family. It is said that she looks just like any other woman but much more beautiful. What sets her apart is her cow like tail. The myth behind Hundra is that she hides her tail, on occasion, to lure men in so that they will marry her. Once they do, her tail will fall off. If her husband is bad to her she will turn terribly ugly and he will regret his decision.
Hundra is seen as a protector of cattle and other animals and also an aspect of Frigg.