The Urulóki (meaning 'fire serpent' in Elvish) were also called Fire-Drakes.

They came forth in the First Age from the pits of Angband, and were part of the great race of Dragons. These Urulóki were fanged and taloned, dreadful in mind and deed, and had breath of flame and sulphur.

The first of their kind was Glaurung, Father of Dragons, but he had many offspring who in turn produced many broods. Ancalagon the black was also of their kind, and the last one left in Middle-earth was Smaug of Erebor.

Of all creatures they were the greatest despair of Men and Elves, and the bane of Dwarves.