Smaug (/smaʊɡ/) is a fictional dragon and the main antagonist in J. R. R. Tolkien 's 1937 novel The Hobbit. He was a fearsome dragon who invaded the Dwarf kingdom of Erebor 150 years prior to the events described in the novel. A group of 13 Dwarves mounted a quest to take the kingdom back, aided by the wizard Gandalf and the Hobbit Bilbo Baggins.