Cold-Drakes were dragons that lacked the great power of all of Middle-earth's most infamous dragons (Ancalagon, Glaurung, and Smaug): the ability to breathe fire. Nonetheless, they were strong foes with their iron-hard scales, wicked claws, and terrible fangs.
Though most were wiped out during the War of Wrath at the end of the First Age, many survived in the far North above the Grey Mountains and in the Withered Heath. As the millennia passed, the cold-drakes multiplied and became a serious threat to the Dwarves in the late centuries of the Third Age. Eventually, war was declared. In TA 2589, Dáin I, King of Durin's Folk, and his second son Fror were slain at the gates of their own hall by a great cold-drake. With the ongoing attacks of these fierce creatures, the majority of the Dwarves decide to migrate eastwards from the Grey Mountains. Soon afterwards, the Iron Hills and the Lonely Mountain became the major dwellings of the Longbeards (the inhabitants of Khazad-dûm). Tolkien gives no hint to the history of the cold-drakes after this time period.
Four hundred years later, at the time of Bilbo Baggins' journey to Erebor, they seem to have left the Grey Mountains (as implied by Gandalf making no mention of them when describing the dangers of that region).
- Some of theories for origin(s) of dragons claim that morphology of cold-drakes may be similar to that of 'dragons' before dragons.
- They may have been animals originally created by Yavanna (and therefore the first dragons) that were then used by Morgoth to breed the much stronger and more wicked Uruloki.
- Land-crawling dragons are sometimes considered physically more powerful than their flying kin by some fans. Some of cold-drakes whose fire-breathing ability did not degenerate as much as 'true' ones, could possibly use breaths of vapor mist or smoke, and magical arts such as "death glance" utilized by Gostir (a speculation from the drake's name etymology).
- What caused cold-drakes to lose the ability to breath fire is unclear. It might have been due to unnecessary to inherit such means of destruction to consume lots of energy after being freed from restraints under Morgoth's rule, or to hide them from Valar and High Elves after surviving War of Wrath. Selection of capabilities to survive is a common phenomenon among real organisms.