Monstrous Nightmare (Books)

The Monstrous Nightmare is a dragon featured in the book. Stoick the Vast and Snotlout both have Monstrous Nightmares.

Description
In the books, Monstrous Nightmares are only the size of a Labrador Retriever, and they can't set themselves on fire. While the movie version has a Pterosaur-like anatomy, its book counterpart looks more like a western dragon.

In How to Train Your Dragon
By unofficial Viking law, only the chief, or the son of the chief, can own one. Despite this, Snotface Snotlout, the nephew of the chief, acquires one named Fireworm (How to Train Your Dragon), while Thuggory from the Meathead Tribe owns another named "Killer".