Of the known dragons the Night Fury is the fastest, smartest, and rarest. Night Fury’s have one pair of wings, sub wings, and tailfins. In flight, a Night Fury's wing to body ratio is unrivaled, this allows it to fly faster, longer and further than just about any of the other dragon. The wing span is approximately 48 feet. Night Fury’s also possess remarkable speed and agility on land, being able to outrun and outmaneuver most other dragons. They are curious creatures that attempt to understand new things they observe and are intelligent enough to attempt to recreate the actions that they see. Night Furies, in comparison to most other dragons, are very capable of communicating, and seemingly understanding human speech. When Night Furies are at locations where their visual sight is limited, making it dangerous to fly, they can use echolocation, visualized as a purple colored sound wave from the dragon's perspective, bounces off all objects and obstacles nearby and allows the dragon to avoid them, even in mid-flight.
A Night Fury by the name of Toothless can be seen in all movies, short movies, and TV series of HTTYD. This specific Night Fury is best friends with Hiccup, and the only one we have seen.
Instead of breathing fire Skrills channel lightning down their metallic spines, firing it from their mouths in a shower of destructive blasts. They can also store this electrical power in their bodies and release it later on. Skrills tend to gravitate towards stormy weather. If you find yourself flying through a thunderstorm, watch out! Skrills are also pretty tough. They can take a lot of damage in battle, and give as well as they get.
We have only seen a Skrill on a few occasions, both being in different seasons of the TV series Dragons.
Snow Wraiths were first discovered by Gothi during an expedition to Glacier Island, the only known habitat of the Snow Wraiths. They have no known vulnerabilities, making them a supremely formidable force to be reckoned with during battle. Their teeth are the sole tool that can unlock the informative Dragon Eye device. Over time Snow Wraiths have adapted to these desolate conditions, such as their all-white coloration and an ability to grip onto ice using claws on their wings and tails.