Who was most responsible for the death of Smaug?

[*Varda*]

It's a hard one to answer, to be perfectly honest. It's basically a chain, something leads to something that leads to something else... you get my drift...

So arguably it could be bilbo because he spotted the hole in the first place, but the thrush told bard where to shoot... who fired the arrow...so it could have been bard.

Personally i voted for Bard, mainly because he fired the shot and killed him - he was the one who actually carried it out, which kind of makes him responsible. The others were just helpers. But i guess it's debatable.