In the "The Hobbit", who kills Smaug?

The story behind the answer

Bard the Bowman of Lake-town kills Smaug by firing his heirloom Black Arrow into a bare patch on the dragon’s left breast. Bilbo had earlier discovered this missing scale, and a listening thrush conveyed the clue to Bard, allowing the precise, fatal shot during Smaug’s attack on Esgaroth. Bard, a descendant of Girion of Dale, later becomes King of Dale.

Memory tip: the three B’s—Bard the Bowman with the Black Arrow. Not Bilbo (the clever burglar who talks to Smaug), not Frodo (from The Lord of the Rings), and not Gandalf (away at the time). Bard’s deed ends the dragon threat and shifts the tale to the conflict over the Lonely Mountain’s treasure.