Originally Posted by Drunkside
i have never seen a dragon killed by anyone but myself, and they have only attacked other characters while im around.
I've seen a dragon try to take on a forsworn encampment and get crushed pretty quickly.
Also if you hide in the tower at the main plot quest where you first get to fight a dragon the Jarl's housecarl and detachment of town guards will kill the dragon on their own. Not very heroic, though.