In mythology, folklore and speculative fiction, shapeshifting is the ability to physically transform oneself through unnatural means. The idea of shapeshifting is found in the oldest forms of totemism and shamanism, as well as the oldest existent literature and epic poems such as the Epic of Gilgamesh and the Iliad. The concept remains a common literary device in modern fantasy, children's literature and popular culture. Examples of shapeshifters are vampires and werewolves.