How to Train Your Dragon Wiki
How to Train Your Dragon Wiki

Threadtails are allergic to their own poison. They often roll around in Dragonberry bushes to scratch their itchy skin.
  World of Dragons  

The Threadtail is a large Stoker Class dragon that first appeared in How to Train Your Dragon 2.

Official Description

Don't touch! This dragon can secrete a poison through its skin when it senses danger. The only problem is the Threadtail is allergic to it too! It spends most of the day rolling around in Dragonberry bushes to relieve the itching.
The Threadtail's unrelenting flames will destroy anything in its way.
  Dragons: Rise of Berk  


The Threadtail was designed and created using a modular system to mix and match preset body parts onto different dragons. It was created from the same base that was used for the Hobblegrunt, Raincutter, Thornridge, Windstriker, and two other unknown dragons.

Physical Appearance


Threadtail Egg.png

Similar to a Snifflehunch's egg, a Threadtail's egg has several lobes at its side. The eggs are usually cyan, speckled with brown spots. The color of the egg also defines the color of the dragon.

Hatchling to Adult

The Threadtail seems to always have bright colors such as bright pink and purple, deep blue with bright green or pale blue with bright yellow. The reason for this colorful appearance is most likely the same as the reason behind the poison dart frogs' bright colors: to warn predators of its poisonous skin. The Threadtail also has a large round frill at the back of its head, and this frill is outlined with round spines which gives it a very crown-like appearance, and it is the same kind of spines can be seen on the nose of this dragon and running down its neck and back. In the movie the Threadtail is seen to have skin covered in many round bumps and lumps that look very similar to something like frog warts, this is most likely a reference to its venomous skin and its allergy to it, meaning those might be caused by scratching.

This dragon's overall body shape seems to be most similar to that of the Thornridge. Long and often colorful dragons, Threadtails have strong necks and tails, as well as a broad wingspan built to take full advantage of the winds and updrafts. They have a prominent frill on the back of their long-jawed head and a ridge of spines along their backs and tails. Their legs are slender and built for running with shorter and denser claws than many dragons of similar size.

Titan Wing Threadtail.png

Titan Wing

Titan Wing Threadtails generally turn a bright shade of orange and tan. Their crowns develop sharper lobes and an increased number of spines line their back and snout. The spots on their wings also fade, giving way to less distinct stripes radiating from its wing bone.



Threadtails can produce non-fatal toxins through their skin to ward off enemies. As mentioned in Almondine's description, one of the effects of this poison is that it causes the victim to experience painful convulsions. According to Almondine's description, the poison of at least some Threadtail individuals smells like marzipan. This defense mechanism comes with a price, for the poisons trigger an allergy and cause the dragons' skin to itch. They can roll around in Dragonberry bushes to relieve the itch. Coarse sand, cold water, and cold wind can also ease their itching. This poison is only produced when the Threadtail is in an agitated state, meaning that, as stated in Overchill's description, poison production is stopped when their bodies are relaxed.


Valka calms Toothless easily.gif

The Threadtail can breathe normal, yellow fire, which can be held in its mouth to illuminate dark places. It can also produce green fire which does not come out in powerful flames, but instead spreads out slowly, like a mist or a fog.

Purple Mist

In addition to its flames, the Threadtail is known to emit a purple mist, A particular individual, Mildew's Strain, breathes purple mist and leaves puddles of shimmery purple liquid on its stand in Rise of Berk. The color of the liquid appears to match that of the Dragonberry bushes surrounding it.

Strength and Combat

Threadtails are able to battle other dragons and carry humans on their backs and longboats that are loaded with a multitude of objects.

Endurance and Stamina

Valka's Dragons vs Drago's Dragons.gif

Threadtail have large amounts of stamina, for they are able to travel great distances, while carrying heavy objects, without showing any signs of exhaustion. As shown by the Threadtail in the second film that they it was able to continue to fly and battle other dragons with armor, proving their endurance is very high.



Threadtails are not immune to their own poison, instead they are allergic to it. They spend much of their days seeking dragonberry bushes to relieve the itch on their skin. The coarse sand and cold water of the beach and the cold winds of the sky can also be soothing, as Sunsoak and Duskgust have respectively found. According to Foliander's description, Threadtails' skin becomes especially itchy during the autumn months. Although, as Overchill has found, Threadtails can simply relax their bodies to avoid their poison being excreted, thus preventing their allergic reactions, this hampers their defenses and could leave them more open to attack.

Behavior and Personality

Threadtails are territorial dragons, and they will protect their homes and their allies at any cost.


How to Train Your Dragon 2

While numerous Threadtails have been seen lighting up caverns and soaring about Valka's Mountain, no individual Threadtails, nor the species, appear to have much significance in the plot.

All the Threadtails from Valka's Mountain fought viciously in the battle against Drago's Army. After Drago's Bewilderbeast defeated Valka's, all the Threadtails bowed to their new Alpha. After they were freed by Toothless from the Bewilderbeast's control, they fought against the giant dragon. In the aftermath, they bowed to Toothless, acknowledging him as their new Alpha.

How to Train Your Dragon: The Hidden World

When the people of Berk decided to move to the Hidden World, all the Threadtails of the island began the journey too, carrying different things, such as ships. They eventually arrived at New Berk, where they settled down for a while.

Many wild Threadtails were among the myriad of dragons in the Hidden World who bowed down in front of Toothless and the Unnamed Light Fury, showing respect for their Alpha.

After Grimmel the Grisly captured Toothless, all the Threadtails from Berk, along with the other dragons, came to their Alpha's help. However, Toothless ordered them to stop when Grimmel threatened to kill the Light Fury.

Fortunately, the Dragon Riders began an attack on Grimmel's ships and freed the Threadtails, along with the other dragons, which returned to New Berk.

When the battle ended, Hiccup realized that the only way the dragons can be safe from humans was for them to go to the Hidden World. After Toothless gave the command to the dragons of Berk, all of them, including the Threadtails, said their farewells to the Vikings and flew off to the Hidden World.

Dragons: Rescue Riders, Season 1

The Threadtail is mentioned in the episode "Home Alone" when Cutter is bragging about himself and his qualities, such as "the instinct of a Threadtail."


Dragons: Rise of Berk

The Threadtail's name was first revealed in this game, along with its class and other background information. The individuals, Mildew's Strain and Foliander, also became available in the game.


  • Asterisk-Transparent.png The official measurements given by DreamWorks Animation do not appear to be realistic when considering the relative sizes the viewer sees within the Franchise. Based on the Model Sheet for the Threadtail, this dragon should be 82 feet (25 meters) long with a Wingspan of 76 feet and 8 inches.
  • The Hobblegrunt model appearing in the game School of Dragons is extremely similar to the Threadtail, rather than the Hobblegrunt model appearing in How to Train Your Dragon 2. This is a huge source of fan discontent, which is seen as an error on the game's part. However, a School of Dragons Narrative Designer, Brian Yoon, clarified that the game submitted two models to DreamWorks for approval and the Threadtail-like model was selected and named.[1] There are currently no plans to alter the name or dragon model in the game.
    • Despite this, the dragon's actual model is labeled as Generic A in the game's files, reflecting that it was created as a 'generic' background dragon. This proves that DreamWorks' approval on the name 'Hobblegrunt' was a mistake. Exactly how the mistake could have happened remains unknown, as the other submitted model clearly depicts a dragon much closer to the Hobblegrunt in the movie.


Threadtail uses Creative Commons Licensed content from the Rise of Berk Wiki page Threadtail. The list of authors can be found on the page revision history (view authors). ROBWiki Logo.png

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