Thunderdrum

The Thunder Drum is the name of a species of dragon. Possesing no fore or back legs, the Thunder Drum relies on its two sets of wings, one primary and one smaller set to the rear, to get around.

According to the Dragon Manual, Thunder Drums are roughly the same size as adult Vikings, and are reclusive in nature, living in sea caves and dark tide pools. The name comes from its main mode of attack/defense. When startled, they can produce a strong concussive sound that can kill a man at close range. Like nearly all dragons in the Manual, they are classified "extremely dangerous, kill on sight."

In the film

 * The Thunder Drum makes its only appearence when Hiccup is reading the Dragon Manual to find information on Night Furies.