2342-2343. Toothless and Hiccup

2323. Gronckle

The Gronckle is the toughest dragon in the dragon world and more than lives up to its looks on the battlefield.
The Gronckle can be slow, lazy, and cranky; it has been known to fall asleep mid-flight, waking only when it plunges into the sea or crashes into a mountain.Because of its tremendous weight and small wings, it would seem impossible for them to fly. However, because the wings of a Gronckle beat at a speed similar to that of hummingbirds' or bees' wings, it is possible for one to sustain flight. In fact, a Gronckle can fly backward, sideways and even hover in place. Its tail can be mistaken for the head if little attention is paid. It is also prone to dragon acne. Because of its large stout body and clubbed tail, the Gronckle somewhat resembles an ankylosaur. They spend the majority of the day sleeping. It has huge jaws which it uses to hold food when carrying it to the dragon mound. It has a rather blunt nose horn and fairly stubby toe claws. Its legs are practically useless in battle, and due to its short tail it has a fairly small attack range.

2278. Monstrous Nightmare

The Monstrous Nightmare is one of the most aggressive, powerful, and stubborn breeds of dragon known to Vikings. Until the Seadragonus Giganticus Maximus was discovered, it was considered the most formidable dragon species.
A Nightmare is usually purple or scarlet and possesses a long, snakelike neck and tail. Unlike some other breeds of dragon, it has no forelegs, and its ground-based locomotion is similar to that of pterosaurs; it can use its claw-tipped wings to "crawl" along the floor.
As it is quick to anger, the Monstrous Nightmare can be counted on to be the first to arrive and the last to leave in a fight. Its signature attack strategy, known as the "Fire Jacket," is to engulf itself in flames (from an external source or otherwise), resulting in an intimidating offensive and defensive maneuver similar in appearance to napalm or other gel-based incendiaries.

2276. Hideous Zippleback

The Hideous Zippleback is a large, two-headed dragon. It is sly and surprising, but certain noises can confuse it and cause it to entangle its heads.
The dragon has two personalities and two minds, one in each head, and one often argues with the other head over what to do. This dragon reminds some vikings of bickering siblings when they aren't running away from it. However, its two heads also give it a deadly weapon that is unique from any other dragon species. One of the dragon's heads breathes a green, flammable gas while the other head uses an electrical spark in its mouth to ignite the gas, creating lethal explosions. The Hideous Zippleback's spine has many bright red lobes that run down it. Occasionally the Zippleback will us these to hold it necks together, making it less intimidating. They have serrated fangs which they use to inject venom for predigestion. Its top teeth are much sharper and are all the same size, while its bottom teeth are very long and stick up above its jaw line.

2131. Terrible Terror

The Terrible Terror is among the smallest of the dragons, but also one of the most feared. It loosely resembles the Common or Garden Dragon and is roughly the size of a small cat. The Terror can crawl into Viking homes, sheds, outhouses and shacks, attacking when its prey is least expecting it. The only warning a Terror gives is the hissing sound it makes just before breathing fire. It is capable of such pinpoint accuracy with its flames that it can be considered the sniper of the dragon world.

Hiccup learns from Toothless that dragons are easily distracted by reflected light on the ground, similar to a cat, and uses this to his advantage to lure a Terror back into its pen during Dragon Training. He also learns that dragons are not as fireproof on the inside as one might think when Toothless spurts a fireball into a Terror's mouth for attempting to steal one of his fish. Before it leaves, Hiccup tosses it another fish and finds that Terrible Terrors are not as fierce as Vikings claim they are after it curls up beside him to sleep. Seeing this makes Hiccup realise that everything the Vikings know about dragons is completely wrong.

2081. Gobber The Belch

Gobber The Belch is a veteran warrior of the Hairy Hooligans Tribe and a long-time friend of Stoick the Vast.
Gobber the Belch is a six-and-a-half foot tall maniac who is tasked with training Hairy Hooligan teens in various skills needed to become a Viking: catching and training dragons, pirating skills, sword-fighting, and rudery (trading insults). He is incapable of speaking in any tone of voice other than a bellow.
In Berk's long wars with the dragons, Gobber has lost his right hand and left leg in battle with the creatures. He has managed to replace his missing limbs with a variety of metal prostheses of his own design and creation. His arm can be interchanged with other items such as a hammer or axe if need be (similar to Alvin the Treacherous in the books).
Since he is no longer able to take an active part in the war, Gobber is left responsible for the village's smithy and armory, keeping the other Vikings supplied with weapons and also with supervising the village's youngsters in Dragon Training.

1687. Seadragonus Giganticus Maximus

The Seadragonus Giganticus Maximus is a type of dragon. These "preposterously huge" fire-breathing Sea Dragons are twenty times the size of a blue whale, and are very dangerous -- they kill for sport. When a Sea Dragon appears on the beach looking for a fight, Hiccup is the only one with a plan to save the tribe.
 Sea Dragons are blue with an orange underside. They have very primitive, dinosaur-like characteristics, with heads that resemble a Tyrannosaurus, narrow sharp teeth, small frills similar to those of Triceratops, thick pillar-like legs like those of Sauropods, and a clubbed tail similar to that of Ankylosaurus. They have red spikes from the back of the neck to the tail and wings with a single membrane. They also have gigantic legs with red spikes on them and five claws on the ends. Sea Dragons are the biggest dragon species ever seen, and they can crush a whole Viking house easily.

1594-1595. Astrid Hofferson and the Deadly Nadder

Astrid Hofferson is a young Viking girl of the Hairy Hooligans tribe who attends Dragon Training with Hiccup and the other Viking teens. She is striking, tough, beautiful and her determined and strong persona makes her hard to impress. Astrid is Hiccup's main love interest in the film. In spite of initially not liking Hiccup or his new found friendship with Toothless, she soon has her opinion changed and helps to try and keep Toothless a secret.
Astrid does not appear in any of the books in the original series and is an original character designed for the film. It is possible she is based on the character Camicazi from the books.

The Deadly Nadder is one of the most beautiful species of dragon. In appearance, the Deadly Nadder is very bird-like: it is bipedal and possesses winged forelimbs. Its small yet keen eyes, equipped with binocular vision, are one of the tools it uses to stalk its targets. Its body is a vivid blue in color, with a light beige underbelly, while its wings are motted with yellow, orange and blue. In front of its eyes is its curved nasal horn, which is often used to batter opponents. Coating the tail is a series of spikes that can inject venom into a target. When relaxed, its venomous tail spikes lay flat, and when alarmed, they are shot upward to intimidate its foe. They can also be used to make a rattling noise which it makes right before it attacks, similar to rattlesnakes.