SmaugSmaug - The dragon which terrorized Middle Earth in the Third Age, he likely was one of the dragons living in the Grey Mountains who stumbled upon the Lonely Mountain after the Dwarves returned to Erebor (see Dragons).

 

"It is almost dark so that its vastness can only be dimly guessed, but rising from the near side of the rocky floor there is a great glow.  The glow of Smaug!  There he lay, a vast red-golden dragon, fast asleep; a thrumming came from his jaws and nostrils, and wisps of smoke, but his fires were low in slumber.  Beneath him, under all his limbs and his huge coiled tail, and about him on all sides stretching away across the unseen floors, lay countless piles of precious things, gold wrought and unwrought, gems and jewels, and silver red-stained in the ruddy light.  Smaug lay, with wings folded like an immeasurable bat, turned partly on one side, so that the hobbit could see his underparts and his long pale belly crushed with gems and fragments of gold from his long lying on his costly bed." ~The Hobbit, chap. XII (Inside Information)