Smaug is the dragon guarding the hoard in J.R.R. Tolkien’s The Hobbit.
Smaug occupies the Lonely Mountain after taking the treasure of the dwarven kingdom of Erebor. The dragon’s attack drives King Thrór’s people from their home and leaves the surrounding region under the shadow of his presence. Years later, Thorin Oakenshield leads an expedition to reclaim the mountain, with Bilbo Baggins joining the company as its burglar.
Bilbo enters the mountain and speaks with Smaug, using riddling and indirect language rather than immediately revealing his identity. During the conversation, Bilbo notices a vulnerable unscaled area on the dragon’s underside. That information is later passed to Bard of Lake-town, who uses it in the final confrontation.
Smaug is sometimes confused with Tolkien’s other dragons. Glaurung and Ancalagon belong mainly to the earlier mythology of The Silmarillion, while Scatha appears in the history of the Rohirrim. Smaug is specifically the dragon of The Hobbit.