Night Fury

The Night Fury is a species of dragon. In the movie adaptation of How to Train Your Dragon, Hiccup's dragon Toothless is a Night Fury dragon. Night Furies are large, sleek, black, have retractable teeth (most likely to prevent their fireballs from catching on the teeth and exploding), and breathe blasts of blue fire which explode on impact in a blue blast. The Night Fury is the rarest species and the most intelligent. Unlike most dragon species, Night Furies have a short neck and lack a nose horn. They also possess a second small set of wings behind their main wings. Before Hiccup knocked Toothless out of the air at the start of the film, none of the Vikings of the Hairy Hooligans had ever seen or fought a Night Fury. This is likely due to the Night Fury's dark color and blue fire (which offers less illumination), which makes it virtually impossible to see at night, which is when it attacks. Additionally, since Night Furies never steal food, they never actually land. The Night Furies' most powerful form of attack is to dive bomb its target. It does this by folding its wings over its legs and stomach,diving towards its target. At the last second, it shoots a fireball and opens its wings, disappearing into the night sky as the fire ball destroys the target, which it apparently never misses.

Night Fury
When Dreamworks started the project How To Train Your Dragon, they wanted the dragons to look more like real animals, and not like the basic lizard-like, green-scaled dragons seen in most movies and books. Therefore, Dreamworks decided to mix different kinds of animals to create the dragons you see on screen. Since Toothless is being trained by Hiccup during the movie, Dreamworks wanted to create a dragon that was more pet-like and familiar to the audience. It is said that the Night Fury is a mix between a cat and a dog. The "cat-like" parts may refer to the Night Fury's pointed ears, yellowish-green slit-pupiled eyes (which can become rounded sometimes), and swift, slinking movements. The "dog-like" parts may be in regards to its (comparatably) smaller stature and friendlier behavior. Simon Otto, head of Character Animation on How To Train Your Dragon, says, "When watching the film with the rest of the crew, we realized that 'dog people' think that Toothless is just like their dog and 'cat people' think he's definitely a cat.'" 

The Night Fury also bears a striking resemblance to the Disney character Stitch. The head, teeth, ears, paws and claws are very similar in appearance, as well as his playful attitude. It is not known if the Night Fury was derived directly from Stitch, or if both characters were simply derived from the same animals. However, considering that Chris Sanders and Dean DeBlois, the directors of How to Train Your Dragon also directed Lilo and Stitch, it is possible that there is a correlation. (Night Fury dragons and other breeds ARE REAL!)

In the Game
The main prowess of a Night Fury in the game is its speed. Night Furies are able to dish out the most combos is a short time. Night Furies have average status. But it is also the dragon with least stamina among all playable dragons, leaving it with a disadvantage. Despite its low stamina though, it is recommended for aggressive or offensive players as well as beginner due to its easy gameplay. Selecting Hiccup as your main character during the game will result in having a Night Fury as your dragon.

Information from the Official How to Train Your Dragon Movie Website
The Official Dreamworks How to Train Your Dragon website contains information on each of the main dragons that appear in the movie. The information for the Night Fury is as follows:

Description

The rarest and most intelligent of the dragon species, the Night Fury is distinguished by its dark color and piercing yellow eyes, as well as its smaller size, heavy chest and short neck. Possessing the largest wing-to-body ratio of all dragons, it can fly higher, faster and longer than any dragon, and its incredible power-to-weight ratio renders it capable of vertical takeoff. Its unconventional fire (a semi-solid mass alight with an acetylene/oxygen flame) explodes its target on impact. Its signature attack mode is executed after sundown and from high altitude-enwrapped in its wings, it dives like a bullet, pulling up at the last moment to deliver one precise and explosive burst...then vanishing back into the darkness. The only warning is the ballistic noise the diving Night Fury makes. Its kamikaze attack, along with its cautious behavior and analytical mind, makes the Night Fury a devastating opponent with an extraordinary success rate. To date, no Night Fury has ever been brought down.

Personality

Reclusive, analytical, inventive and the most intelligent of the known dragon species.

'''Hah! Factor'''

PICKY EATER

If a Night Fury eats something it doesn't like, stand back. Flaming food flies fast.

'''Ahh! Factor'''

KAMIKAZE BOMBER

Using the night to hide its dark hide, it dive bombs villages, ships and armies virtually unseen.

Trivia

 * The sound of Night Fury and Toothless is a combination of various sounds, including Supervising Sound Designer Randy Thom, Elephants, Horses, Tigers, and even Domestic Cats.