Phenomenon and/or belief found in numerous cultures all over the world, closely related to belief in witchcraft, werewolves and other "were" creatures.

In norse folklore, a person who can travel in the shape of an animal and learn secrets, or take on certain characteristics of an animal. The person is then said to be wearing that animal's hide. The most well-known example of the latter is the warrior who takes on the strength and stamina of a bear, called "bearpants" or berserker. The use of an animal shape for other purposes was considered unmanly, and such seidmen were frequently cast out or summarily executed. Female practitioners got off more lightly, until the witch trials began in the middle ages and renaissance.