The world of J. K. Rowling's seven Harry Potter novels is inhabited by not only witches, wizards, and Muggles, who are ordinary folk generally oblivious to and protected from magic, but also a vast assortment of real and imaginary creatures. Young wizards bring owls, cats, and the odd rat to Hogwarts School of Wizardry and Witchcraft, where Harry enrolls at the age of eleven. In The Care of Magical Creatures classes, Keeper Rubeus Hagrid's misplaced love of the exotic leads him to domesticate a hippogriff and engage in dangerous breeding experiments. In Professor McGonagall's Transfiguration classes, students begin by changing porcupines into pincushions or tortoises into teapots. A very few wizards have the ability to become Animagi, and can transform at will into a particular animal. And Professor McGonagall herself initially appears in the books as a tabby cat (SS, 2).

Of course, some of these references to real and imaginary creatures derive from folklore about magic, but Rowling's general conformance with Christian doctrine in characterizing the struggle between good and evil also invokes the medieval literary tradition of the bestiary, which is perhaps best defined as “a compilation of pseudoscience in which […] fantastic descriptions of real and imaginary animals, birds, and even stones were used to illustrate points of Christian dogma and morals.” The specific model for the medieval bestiaries was the fourth-century Greek Physiologus, which derived its descriptions from the writings of earlier Greek and Latin authors such as Aristotle and Pliny the Elder.