"My armour is like tenfold shields, my teeth are swords, my claws spears, the shock of my tail is a thunderbolt, my wings a hurricane, and my breath death!" —Smaug
Smaug was the greatest and most powerful Dragon in the latter part of the Third Age, and one of the last of the great Fire-drakes; intelligent and cunning, he could speak in the Common Speech of all races and was able to put people under the dragon-spell with his glare, compelling them to do his bidding. His invasion of the Lonely Mountain made him extremely wealthy, as the lonely mountain was once home of the dwarves, and he lived there for many years, until he was slain during the events of The Hobbit.
"Revenge! Revenge! The King under the Mountain is dead and where are his kin that dare seek revenge? Girion Lord of Dale is dead, and where are his sons' sons that dare approach me? I kill where I wish and none dare resist." —Smaug
In the twenty-eighth century of the Third Age, the chronologies of the Westlands tell of how the mightiest Dragon of the Age came from the north to the great kingdom of the Dwarves in Erebor, the Lonely Mountain. The fire-drake called Smaug the Golden was vast and bat-winged and a fearsome bane to Dwarves and Men. With consuming Dragon-flame, Smaug ruined the city of the Men of Dale and broke the door and wall of the Lonely Mountain. The Dwarves then fled or were slain and Smaug took the riches of the mountain and the town: gold and gemstones, mithril and silver, elf gems and pearls, the many faceted crystals of emerald, sapphire and diamond, as well as the Arkenstone.
Smaug releasing his blast.
For two centuries, Smaug ruled Erebor uncontested, laying waste to the lands around the mountain. Yet in the year TA 2941, a company of 14 adventurers led by the heir of the former Dwarf-kingdom, Thorin Oakenshield, and his Hobbit 'burglar' named Bilbo Baggins. They approached the Fire-drake by stealth and were surprised to find that Smaug was larger than they had expected. He was armored as all of his race with scales of impenetrable iron, but in wariness, he protected his soft underbelly from assault: as he lay sprawled upon the wealth of his hoard he allowed diamonds and hard gemstones to imbed in his belly, armoring his only weakness.
During a confrontation with the dragon, Baggins noticed one missing scale in the monster's bejewelled belly. With this invaluable information, he escaped the Mountain and was overhead by a friendly bird (a thrush), which carried the secret to Bard the Bowman in nearby Lake-Town.
The burgling of the Hobbit aroused Smaug, and he came out in fiery wrath and loosed his flame upon the land. In vengeance, he came to Esgaroth (Laketown); the town built on the Long Lake and devastated it. In the midst of the wreck, Bard the Bowman, heir to the throne of Dale did his best to rally the defenders. Bard, guided by the secret of the Smaug's weakness, shot a magic black arrow into the beast's chest. Screaming in fury and pain, Smaug fell, crashing into the flaming ruins of Laketown.
After Smaug's death, Thorin and Company claimed the treasure as theirs by birthright. This created a conflict with Bard and the Elvish king Thranduil of Mirkwood, who each wanted a portion of the gold as reimbursement for all the damage Smaug had caused their kingdoms over the years. Thorin refused to share the treasure and declared war on both of them.
It is said that a vast fortune in gemstones lay with Smaug's rotting carcass amongst the pilings of old Lake-Town, but few had the courage to dive for them in later years. With no Dragon to contend with, the survivors of the town rebuilt -- on dry land next to the lake.
According to Gandalf, it was fortunate that Smaug had been slain, since had he lived he would almost certainly have come under Sauron's control and been used to assault Rivendell and destroy the elves of Mirkwood.
Smaug's scales rendered him almost invulnerable, and made even stronger by jewels plastered to them from decades lying on them. However, when Bilbo Baggins confronted him in his lair, he discovered a bare patch on his underbelly. Bard used this to defeat him when fired his Black Arrow into him.
Portrayal in adaptations
In the 1977 animated version of The Hobbit, Smaug was voiced by Richard Boone, and his head looked much like that of a cat.
In the 2003 video game release, Smaug was voiced by James Horan.
In his youth, his name was Smaug the Golden implying that dragons scales darken with maturity.
Behind the Scenes
In the books, the name Smaug is presented as a translation of the "original Dalish" Trâgu, and is related to Sméagol/Trahald. According to Tolkien, the name Smaug is "the past tense of the primitive Germanic verb Smugan, to squeeze through a hole" (Letter No. 31); others have noted that it has echoes of "smoke" and "smog", though this connection is illusory at best, since in Tolkien's phonology, the "au" phoneme is pronounced like the "ou" phoneme in sound or house. Therefore names such as Sauron or Smaug are pronounced like Sow-ron or sm-ow-g.