Glaurung is the fictional father of dragons in J.R.R. Tolkien’s The Silmarillion.
Glaurung is introduced in Tolkien’s mythology as the first of the great dragons bred by Morgoth. He is a wingless, fire-breathing dragon and a major enemy in the story of Túrin Turambar. His power includes deceptive speech and the ability to influence or paralyse those who face his gaze.
The tale of Túrin gives Glaurung an unusually important role in Tolkien’s legendarium. His manipulation of Túrin and Nienor contributes to the tragedy of the narrative, making Glaurung more than a simple monster or battlefield opponent.
Smaug is Tolkien’s dragon from The Hobbit, while Ancalagon the Black is a later and much larger winged dragon associated with the War of Wrath. Those names are plausible alternatives, but Glaurung is the specific figure known as the father of dragons.