Red Death

The Red Death is a Seadragonus Giganticus Maximus dragon and the main antagonist of Jaden learns How To Train Your Dragon. It is the "queen" to the other dragons. The other dragons have to raid the viking village and feed it or they'll be eaten themselves. Hiccup and Astrid discovered the Red Death during a flight on Toothless. Later when the vikings discovered the dragons nest, they attempted to stop the dragon, but it was too big and powerful to kill. But Hiccup and Toothless were able to finally kill the Red Death by attacking it from the inside, thus bringing harmony between the vikings and dragons.