Smaug is a fictional dragon from The Hobbit. He is the main villain of the J.R.R. Tolkien book and it's adaptations. The author called him a "most specially, greedy, strong and wicked worm".
Fictional biography change
Smaug is one of the most feared dragons on Middle-earth. He decided to sleep in a pile of gold until Bilbo Baggins woke him up. Smaug knows that Bilbo is after the Arkenstone. He left the area and decided to fly to Lake-town and ravage it with fire. He was killed by Bard the Bowman with an arrow.
Peter Jackson trilogy (2012-2014) change
In The Hobbit movie trilogy, Smaug's motion capture and voice were done by Benedict Cumberbatch. He is digitally created by Weta Digital and is considered one of the most impressive features of the trilogy, specifically the end of the second movie. In the third movie, his death helped Sauron let his armies roam free.
Other media change
Smaug, voiced by Benedict Cumberbatch became an interviewed guest for a December 2014 episode of The Colbert Report with clips from the third movie.