A variety of magical creatures are depicted in the fictional universe of Harry Potter, which is drawn from various types of media. Magical creatures appear in the Harry Potter novels and their film adaptations, in the Fantastic Beasts film series, in other books by J. K. Rowling, and on the website of the Wizarding World media franchise. In 2001, Rowling released Fantastic Beasts and Where to Find Them, which serves as a guidebook to the creatures described in the fictional universe. Some of these creatures were invented by Rowling. Others are derived from sources such as Greek mythology, English and Celtic folklore, and the works of Roman historians.