I two-shot a dragon as an archer, but to be fair, it was only because I knew exactly where he was because he'd just killed me and I was giving it another go. Managed to get a huge sneak bonus, took down 2/3 of his life in one shot, then got lucky and shot him out of the sky. He crashed to the ground and there was this huge furrow where his body had slammed into the dirt, it was awesome.
Yeah, the death furrow thing is awesome.
Playing as a Khaijit with most of my armor enchanted to either be +sneak or +marksmanship, and playing on easy because I like games to be simple and easy, I can regularly oneshot dragons.
I have a Legendary Daedric Bow with a ... I think it's Lightning damage. The one where it does just straight damage without any extre effect.
Does something like 500 base damage per shot, plus arrows, plus like another 100 damage or so from the enchant. Then my sneaking bonus, and my glove sneak attack bonus.
Something like 1700 damage a shot once all the bonuses are applied.