Green Death (Books)

The Green Death is the most well-known Seadragonus Giganticus Maximus. In the film, it is known as the Red Death (though the soundtrack lists "Battle with the Green Death" as the background music to the final battle with the enormous dragon).

In the Books
In the first book, the Green Death arrives on long beach with a smaller Seadragonus Giganticus Maximus (which it eats later on). Hiccup is sent to meet with it and asks if it comes in peace or war (as he is the only one who can speak Dragonese). The dragon says he comes in peace but that he's still going to eat them all. The Green Death and Hiccup discuss Singing Suppers, but during the conversation the Green Death moves in to eat Hiccup. Just as this happens the Green Death yawns, and decides he's too tired to eat Hiccup right now, stating that he should come back in a few hours to be eaten. Hiccup then leaves and tells the tribe that the Green Death, while coming in peace, will still eat them. With the help of the other Hooligan and Meathead boys and their dragons, Hiccup creates a plan to kill the Green Death with the help of a third Seadragonus Giganticus Maximus, the Purple Death, which they trick into helping them. In the following battle the Purple Death is killed but the Green Death is fatally wounded. In anger, the Green Death swallows Hiccup whole. Fortunately, Hiccup avoids being digested by grabbing and holding on to a Roman spear stuck in the dragon's throat. While inside the Green Death, Hiccup discovers the fire holes (a dragon's source of fire) and blocks them with his helmet. Due to this, the Green Death blows up when it tries to burn Stoick, Hiccup and Toothless. Its death makes Hiccup a hero in the eyes of his tribe.

In the Film
In the movie adaptation, the Seadragonus Giganticus Maximus is renamed the Red Death. It serves primarily as the movie's indirect main villain/antagonist; it was the leader of the dragons living within the Dragons' Nest. Initially seen dwelling in the volcanic interior of the Nest, the Red Death accepts all of the livestock its 'dragon servants' bring it as its own meal and eats anything that contributes little to nothing (as seen with a sole Gronckle who donates a single fish).

The Red Death isn't seen afterward until the climactic battle between it and the Vikings. Stoick, who strapped Toothless to a ship and used him to find the Nest, first arrives with the rest of the village on the island housing the Nest and only succeeds in scaring off the dragons that serve the Red Death. Enraged, it soon breaks through the mountainside and terrorizes the Vikings. The teenage Vikings soon arrive, however, on their own dragons (save for Hiccup, who is temporarily riding with Astrid on a Deadly Nadder). While the other viking teens distract the Red Death, Hiccup nearly drowns after trying to save and unchain Toothless on one of the boats to which the Red Death had set fire when the both of them are saved by Stoick. Hiccup, along with Toothless, takes off to confront the Red Death.

After circling the island once, Toothless annoys the Red Death by launching a fireball at the monster's side. The enraged dragon then pursues Toothless and Hiccup into the air where Hiccup decides to use the heavily clouded sky as a cover. Toothless then attacks the Red Death in the clouds with a barrage of fireballs aimed toward its thin wings. The Red Death angrily sets the entire sky, as well as Toothless' makeshift tail, on fire. After seeing this, Hiccup and Toothless decide to finish the monster once and for all by skydiving towards the island with the Red Death hot on their heels. With the beast just above them, Toothless launches a fireball directly into the flammable gases within the Red Death's mouth. The gases ignite violently inside the Red Death as it discovers that it cannot pull out of its skydive with its wings in tatters. The Red Death crashlands onto the island and combusts in a bright, fiery explosion.

"This ultimate monster, seen pursuing Toothless and Hiccup, is the most vicious. According to legend, it lives 2,000 years and, before it dies, lays 3,000 eggs. The hatchlings fight each other to the death, a process that can take up to 100 years, until only one survives. “All dragons have a blind spot,” Sanders says. “Except this one. That is one reason we gave him six eyes instead of two. The other reason is that we wanted him to be just generally upsetting. This one is our Godzilla.”"

Fun Fact
In the movie, Tuffnut makes an allusion to Beowulf by calling Red Death 'Grendel'.