Fireworm makes no appearance in the film; however, a Monstrous Nightmare named Hookfang is trained by Snotlout. Hookfang is the name of Stoick's in the books. Unlike his Fireworm, Hookfang is male and has a very different personality. Unlike Hookfang, Fireworm is very obedient towards Snotlout. Hookfang in the movie seems to show grudging respect towards Hiccup, whereas Fireworm in the book shows as much animosity as her owner towards him.