Smaug is the dragon who guards the treasure in The Hobbit. He has occupied the Lonely Mountain since driving the Dwarves of Erebor from their kingdom.
Smaug’s attack on Erebor took place before the main action of the novel. He seized the Dwarves’ immense hoard and settled beneath the mountain, leaving the nearby town of Dale ruined. Thorin Oakenshield later leads an expedition to reclaim the mountain and its treasure, with Bilbo Baggins serving as the burglar.
Bilbo enters Smaug’s lair and speaks with the dragon in a famous riddle-like conversation. During that encounter, Bilbo notices a bare patch in Smaug’s otherwise armored underside. The information is passed to Bard of Esgaroth, who uses a black arrow to kill the dragon.
Smaug is not the first dragon in Tolkien’s wider mythology. Earlier creatures include Glaurung and Ancalagon the Black, but neither guards the treasure of Erebor in The Hobbit. Smaug’s name is connected to an old Germanic verb meaning “to squeeze through a hole.”