Smaug is the dragon who rules the treasure hoard in J.R.R. Tolkien’s The Hobbit.
Smaug occupies the Lonely Mountain after driving the dwarves of Erebor from their kingdom. He sleeps on the enormous treasure accumulated by the dwarves and becomes the central danger of the company’s quest. Bilbo enters the mountain, speaks with Smaug, and notices a vulnerable place in the dragon’s armor.
That weakness allows Bard the Bowman to kill Smaug with the Black Arrow when the dragon attacks Lake-town. The dragon’s death does not end the conflict, because the treasure claim and the attack on Erebor lead to the Battle of the Five Armies.
Smaug is distinct from Tolkien’s other dragons. Glaurung appears in The Silmarillion’s legend of Túrin, Ancalagon belongs to the First Age, and Scatha is a different dragon associated with the Grey Mountains.