Toothless' Nemesis

This is an unnamed Whispering Death, who holds a serious grudge with Toothless. He appears in the Riders of Berk episode, What Flies Beneath.you can see a Night Fury bite mark on its tail.It can shoot spikes from any part of its body like any other Whipering Death.

Dragons Riders of Berk
This Whispering Death appeared in episode 14 (What Flies Beneath). He held grudge against Toothless who had bitten him before Toothless and Hiccup became friends, and got into two fights with Toothless. In the first one, he showed himself to the gang. Toothless wrestled with the Whispering Death until he shot him in the leg with spikes. In the second fight Hiccup was prepared to help Toothless, but Toothless refused and tried to manage on his own. Without Hiccup Toothless was unable to fly properly, so the Whispering Death knocked him out of the sky and used his fire to send him onto a ledge. The Whispering Death then tried to send Toothless into a canyon, which would kill him. Only by accepting Hiccup is help was Toothless able to defeat the Whispering Death. Toothless spared the Whispering Death, and it fled back to it's tunnel.

Abilities
This one have shown to have great abilities worthy dragon to proven Toothless and possible better then this kind.

Endurance and Stamina : He can take a lot of damage from toothless as well as other dragons, while continually getting up after he had been hit. So many attacks able to be able fly and burrowing no signs of trouble.

Agility: He is quite agile, being able to dodge Toothless's "Plasma Blasts" in a blink of an eye.

Acrobatics: He is shown to have very flexible body, making it easier to dodge attacks, his reflexes are are great, making it harder him to be hit.

Intelligent: He can tell that toothless was not able to fly at all, making him a vulnerable target, thus, the Night Fury would be easy to defeat.

Senses: His senses of smell was shown to be strong enough to find toothless and he also strangely was able to resist dragon-nip.

Fighting style: He was shown to be a worthy opponent for toothless, by using his abilities as well as strategy to almost kill toothless.

Burrowing: He has shown to be great to make tunnels. Using this way against his enemy's to surprise them to attack.

Speed: He moves in high speed mostly by underground.

Weapons
sharp teeth, horn, spines, tail, and head

Trivia

 * It's possible this and Alvin's dragon are one and the same given the fact that they are the same color.