Flightmare

The Flightmare is a dragon that appears in Dragons: Defenders of Berk. It appears in the episode Fright of Passage.

Appearance
The Flightmare is a medium-sized dragon that has a very ghost-like appearance. Its body is covered in small spots that almost resembles the night sky. Also it looks like a mix of a Skrill and a Night Fury,but glowing.

Abilities
The Flightmare's body glows by eating algae that shines along with the Northern Lights. It can strike with a mist that paralyzes its prey to give itself enough time to return and finish it.

Defenders of Berk
The Flightmare first appeared in Fright of Passage, terrorizing Berk every ten years. Last time, Astrid's uncle, Fearless Finn Hofferson, faced the dragon and seemed to be frozen by fear, shaming her family's name. Astrid and Hiccup set out to find the Flightmare, where Astrid tried to fight it, but was frozen by the dragon's mist. They learned that victims of the dragon were not frozen by fear, but paralyzed. They soon discovered a stream of glowing algae that gives the Flightmare its glow, as well as other dragons (as discovered by Toothless). Realizing that the Flightmare only attacked Berk because it thought the Vikings were threatening its food supply, Hiccup, Astrid, and Fishlegs created a new channel for the algae to flow into the sea, and the Flightmare left Berk. Hiccup explained to the village what they learned about the dragon and that Finn Hofferson truly was fearless, restoring honor to Astrid's family.

Trivia

 * The Flightmare is the only known dragon that appears once every 10 years.
 * The Flightmare is the first herbivorous dragon to be seen as it only feeds on algae.
 * The Flightmare's design is similar to that of the Skrill.
 * The Flightmare is seen in the   Dragon Manual  next to the  Snaptrapper  and   Hideous Zippleback .  This means it is probably a Fear-class dragon, which would also mean it is the only known Fear-class dragon to not have more than one head.  Of course, the Dragon Manual doesn't seem to list the dragons in any particular order. But the Vikings know when it turns up. Every ten years. and Fear class dragons turn up when you least expect them.
 * The Flightmare has a tail that looks like a Night Furies.
 * For a particular reason the flightmare is not in the dragon manual in the Defenders of Berk website and it is already 5 episodes far.
 * It is the only dragon that glows other than the fireworm queen

Gallery
http://24.media.tumblr.com/5a0b2f18291b95b4f720dac8c60af12a/tumblr_mv8jtrrRWu1rletc5o1_1280.jpg