Smaug is the title character’s principal nemesis in J.R.R. Tolkien’s The Hobbit.
Smaug is a powerful dragon who occupies the Lonely Mountain and guards the enormous treasure taken from the Dwarves of Erebor. His arrival drove King Thrór’s people from their kingdom, creating the central historical grievance behind Thorin Oakenshield’s quest.
Bilbo Baggins enters the mountain as the company’s burglar and speaks with Smaug. During their conversation, Bilbo notices a bare patch in the dragon’s jewelled hide. The information is later used by Bard the Bowman, who kills Smaug with the Black Arrow after learning of the vulnerable spot from a thrush.
Smaug is not the same character as Sauron, the principal evil power in The Lord of the Rings. Tolkien’s mythology contains several dragons, including Glaurung and Ancalagon, but Smaug belongs specifically to the narrative of The Hobbit.