What name did J.R.R. Tolkien give the father of all dragons?

J.R.R. Tolkien called Glaurung the father of all dragons.

Glaurung is a major dragon of the First Age in Tolkien’s legendarium. He first appears in the history of Beleriand and serves Morgoth, the principal dark power of the First Age. Unlike Smaug, Glaurung is part of the older mythology later associated with The Silmarillion.

His most important story is the tragedy of Túrin Turambar. Glaurung uses deception and a powerful gaze to manipulate Túrin and Nienor, turning their family history into one of Tolkien’s darkest tales. The dragon is eventually killed by Túrin with his sword Gurthang.

Glaurung is often confused with Ancalagon, the largest winged dragon, or Smaug, the dragon of The Hobbit. Those are different creatures. Glaurung is the earliest fully developed dragon in Tolkien’s mythology and is specifically identified as the father of dragons.