Smaug's ability to speak, the use of riddles, the element of betrayal, his enemy's communication via birds, and his weak spot could all have been inspired by the talking dragon Fafnir of the Völsunga saga. Shippey identified several points of similarity between Smaug and Fafnir.
They were apparently quite linguistically skilled and loved “riddling talk.” I imagine they learned the Westron from the Dwarves in the far north.
Bilbo does confront Smaug the dragon and, like his encounter with Gollum, he matches wits with him in conversation. During the conversation, however, he looks for the vulnerable spot on Smaug's body. Bilbo knows Smaug must be killed and, rather than avoiding it, Bilbo develops a strategy for accomplishing it.
As well as "dragon", Tolkien called them "drake" (from Old English draca, in turn from Latin draco and Greek δράκων), and "worm" (from Old English wyrm, "serpent", "dragon"). Tolkien named four dragons in his Middle-earth writings. Like the Old Norse dragon Fafnir, they are able to speak, and can be subtle of speech.
Smaug did not know that Bilbo had the one ring. Unlike the Nazgul, Smaug couldn't detect the presence of the ruling ring. He had no way of knowing that Bilbo had it, was using it, or that it was the power of the ring that made it impossible for Smaug to find Bilbo.
Smaug was considered to be the last "great" dragon of Middle-earth. Sauron allied with Smaug and intended to use the dragon's powers against the people of Middle-earth. But before that could happen, Smaug was slain by Bard the Bowman.
Smaug's dragon-fine would not have been hot enough to destroy the One Ring. The malevolence that Sauron put inside of the Ring could only be destroyed in the Cracks of Doom, so Frodo was compelled to make the journey to Mordor.
Yet, with Smaug being a dragon, he may have shared the same traits as real-world reptiles -- most notably, their ability to go long periods without eating. Many reptiles have a form of hibernation called brumation, where they'll slow down to conserve energy over winter and not require any food.
Smaug is still a huge and devastating beast, especially compared to little Bilbo Baggins, but Balerion's height comes out victorious. However, Smaug was far from the largest Dragon in Middle-earth, as some are said to be as big as a mountain.
Smaug asks Bilbo's name. Bilbo doesn't want to give Smaug his name for fear of evil spells, but he also doesn't want to refuse Smaug's request for fear of angering the dragon (neither would we). So Bilbo calls himself a number of fancy names – "Barrel-rider" being the primary one.
“Smaug is super intelligent,” Jackson says. “Unlike Gollum who's a messy, scattered kind of character, Smaug is smarter than Bilbo is. He's very, very cunning. He plays psychological games with Bilbo.
In the conversation between Smaug and Bilbo, Bilbo calls him "Smaug the Tremendous", "Smaug the Chiefest and Greatest of Calamities", "Smaug the Mighty", "Smaug the Unassessably Wealthy", "Lord Smaug the Impenetrable" and "Your Magnificence", and later Bilbo refers to him as "Smaug the Terrible" and "Smaug the Dreadful ...
Undeniably, Smaug is the Greatest Dragon left in Middle Earth during the Third Age. Yet, he is not the strongest in its history. That title falls to Ancalagon the Black, the largest dragon ever to have existed in Middle-earth.
Drogon Daenerys Targaryen's mount from Game of Thrones, ended up being 50 meters long, plus or minus 10. Smaug from The Hobbit is a staggering 140 meters long, give or take 15.
Smaug Lost Two Legs
The idea was to get the fear through his bulk. In fact, if you go back and look at the first film and the scenes that he was in, he was actually a four-legged dragon because we just had him stomping through Erebor in all of those flashback scenes," Letteri said.
Smaug was at very least ~180 years old by the time he was slain.
Towards the end of An Unexpected Journey, a thrush appears to the Dwarves and it is considered as a sign of hope. The bird flies to the Lonely Mountain and breaks an nut, which wakes Smaug.
Smaug was the last great fire-drake, but not the last of all. After his death, others of like kind apparently still survived in the world, but none came close to Smaug in power.
In an attempt to defeat Smaug, the dwarves try to drown him in liquid gold. Yup, that's right. Apparently, there was a whole bunch of gold just waiting to be melted down and then poured into a GIANT cast of a dwarf statue.
For 171 years, Smaug hoarded the Lonely Mountain's treasures to himself, staying within the mountain, until a company of Dwarves managed to enter the Lonely Mountain and awaken him from hibernation.
It wouldn't be easy–the most common descriptor of a dragon is “fire-breathing,” after all. But unlike other aspects of the book and now the film that are wholly magic, Smaug's burning breath is actually one of the least magical, and can be wrangled into plausibility.
So, one glimpse into Smaug's eyes and the Balrog falls under the spell. Even if it's just for a second—a moment of hesitation or distraction, it'd be enough. Smaug would snatch up Durin's Bane and gobble him up with his sword-sharp teeth (and we know swords can kill Balrogs). There you have it.
Gandalf absolutely could have killed Smaug in a one-on-one fight. The grey wizard fought and defeated the Balrog of Moria, and a dragon was a lesser evil than that. As proof, Morgoth -- the original Dark Lord of Middle-earth -- created and bred dragons to his evil purpose in the First Age.
As for Sam, his resistance likely has to do with his innate goodness and loyalty. His love for Frodo helped him to overcome the pull of the Ring and his inner pureness was never fully pierced by the Ring.