Fenrir also appears in at least three Young Adult fiction books. First, he inspired the werewolf Fenrir Greyback in the "Harry Potter" series by J.K. Rowling. He also appears in the form of Fenris Wolf in "Magnus Chase and the Gods of Asgard", by Rick Riordan, as the main adversary in the first book of the series. His influence is also seen in Sarah J. Maas' "Throne of Glass" series in the character Fenrys, who can transform into a large wolf.