Smaug is the dragon guarding the Lonely Mountain in J.R.R. Tolkien’s The Hobbit.
Smaug conquered Erebor, the Dwarves’ wealthy kingdom, and drove its people into exile before the events of the novel. He sleeps on the treasure hoard beneath the mountain and reacts violently when Bilbo Baggins enters his lair. Bilbo learns that Smaug has a vulnerable area in his armour-like underside, a detail that helps Bard the Bowman defeat him.
Smaug is one of Tolkien’s best-known dragons, but he is not the first or greatest dragon in Tolkien’s mythology. Glaurung appears in the earlier stories later collected in The Silmarillion, while Ancalagon the Black belongs to the First Age. The Hobbit presents Smaug as intelligent, vain, eloquent, and dangerous rather than as a mindless monster.