In J.R.R. Tolkien’s novel The Hobbit, Smaug is the dragon guarding the treasure of Erebor.
Smaug attacks the Dwarf kingdom of Erebor before the main events of the novel, driving King Thrór’s people into exile. He then occupies the Lonely Mountain and sleeps among its enormous hoard, while the nearby settlement of Dale lies ruined. Thorin Oakenshield later leads a company of Dwarves to reclaim their homeland, with Bilbo Baggins serving as their burglar.
Bilbo discovers that Smaug has a vulnerable patch on his underside and reports this weakness after speaking with the dragon. The information reaches Bard, the bowman of Lake-town, who uses the Black Arrow to kill Smaug. The dragon’s death begins a wider struggle over the treasure, involving Dwarves, Men, Elves, Orcs, and Eagles.
Smaug is sometimes confused with Tolkien’s other dragons, especially Glaurung from The Silmarillion and Ancalagon the Black from the First Age.