- "Despite their small size, Grim Gnashers love nothing more than to sink their thousands of teeth into smaller and weaker dragons.
Sneaky and opportunistic, Grim Gnashers circle above their injured prey like carrion birds. Even though they hunt in packs, Grim Gnashers prefer to feast on a dragon that can't defend itself, rather than take on a healthy dragon. Yet Grim Gnashers are just as deadly with their long-range attacks. Possessing a shark-like ability to regenerate row after row of sharp teeth, these dragons spit out fiery blasts of fangs with remarkable precision and accuracy. But perhaps the most dangerous thing about Grim Gnashers is their ability to plan and communicate with each other to outsmart their quarry."
Hatchling to Adult
Grim Gnashers resemble Grapple Grounder as they have similar long, serpentine bodies albeit thicker, a small head and four legs. They have three main sets of horns on their head, complemented by more allow its neck and back. In addition, they have a long nasal horn and a distinct under-bite with small rows of pointy teeth, giving it a sinister appearance. Covered with prominent, iridescent purple scales, they have a paler underbelly but more vibrant coloration on their back and wings.
The leader Grim Gnasher has purple scales, red stripes on its back and red wings, differentiating itself from the rest of the group.
Much like sharks, Gnashers have the ability to shed and regenerate as many rows of teeth in their lifetime. They are said to have a thousand teeth. Furthermore, they can attack by shooting them in their blasts with incredible precision.
Teamwork and Communication
Their remarkable communication skills are the core of their extraordinary teamwork. They are able to plan and communicate to plot against their prey. As such, they tend to hunt in packs and ambush their prey. Similar to the Speed Stingers, the Grim Gnashers have a leader (or an alpha) whose orders they follow.
Behavior and Personality
These dragons are scheming and cunning as they tend to plot against their prey. Furthermore, they exploit the weaknesses of the old and sick dragons of Vanaheim, a divine funeral ground for dragons to spend their last days, despite being perfectly healthy. This behavior is likened to that of a vulture who circle and taunt weaker prey and consume carrion. As such, they leach off the dragons' physical immobility and strengths and have thus became the enemies of Sentinels.
Grim Gnashers are introduced in the episode, "Searching for Oswald... and Chicken". Hiccup and Fishlegs return to Vanaheim, along with Dagur, following up on clues from Oswald's Diary. They encounter the Grim Gnashers there, a predatory dragon-eating species preying on the weak and dying dragons on the island. They also find out that Oswald had made it his mission to assist the Sentinels protecting the ailing dragons from these predatiors. There was also a diagram of a Grim Gnasher on a wall in Oswald's hut in Vanaheim.
- Their ability to shoot their teeth might be based on those of a Poison Darter's or Razorwing's from the book series.