Smaug is the dragon guarding the treasure in J.R.R. Tolkien’s The Hobbit.
Smaug seized the Lonely Mountain and its hoard from the Dwarves of Erebor before the main events of the novel. The displaced king, Thrór, and his descendants remained connected to the lost kingdom, and Thorin Oakenshield eventually led a company to reclaim it.
Bilbo Baggins enters the mountain as the company’s burglar. His conversations with Smaug reveal the dragon’s intelligence, pride, and ability to use language deceptively. Bilbo also notices a vulnerable patch in Smaug’s armor-like underside, information that helps Bard the Bowman defeat the dragon during the attack on Lake-town.
Smaug is sometimes confused with other dragons from Tolkien’s wider mythology, such as Glaurung and Ancalagon the Black. Those figures belong to earlier First Age stories. Smaug is specifically the dragon of Erebor in The Hobbit, and his death changes the political balance around the Lonely Mountain.