Smaug (known by such titles as "The Magnificent", "The Golden" and "The Terrible") is one of the last great dragons of Middle-Earth. He was bred by the first Dark Lord, Morgoth Bauglir, through the first dragon, Glaurung. He is the primary antagonist (or in the Peter Jackson films, one of the primary antagonists) of Tolkein's "The Hobbit".

Many years ago, Smaug invaded the Dawrven city of Erebor; Mercilessly slaughtering its inhabitants and driving the surviving dwarves away from their home. He then took the mountain city and all its wealth (including the most precious of all, The Arkenstone) for himself. For several decades, he was content in sleeping on his conquered treasure, in which several golden pieces and gems were embedded into his already nigh impenetrable scales.

He was awoken from his slumber by the hobbit, Bilbo Baggins, who was scouting the enormous treasure chamber by order of the dwarves he was travelling with. Upon learning that the people of Lake Town had aided the group, the enraged Smaug flew to Lake Town and began burning it to the ground. However, he was finally slain by Bard the Bowman, who killed him through shooting his arrow into an exposed patch of his breast.

In the films, he is voiced by Benedict Cumberbatch

Smaug is one of the most iconic Western dragons in literature, and many modern depictions of Western dragons are heavily based on him in both appearance and behavior.