I keep reloading an old save whenever Lydia dies, so I'm not sure it counts. I've killed her twice with Storm Call (the fucking lightning never hits the god damn dragon FFS) and once when she ran right in front of my power attack.
I would just leave her dead, but I didn't go to all the trouble of crafting and improving a second complete (and upgraded) set of Dragonbone Plate armor + shield for her to up and die on me.
That said, the primary reason I crafted said dragonbone armor was because I had a truly ridiculous amount of dragon remains. I keep stumbling across random-encounter dragons and what I term "roosts" (places on the map with a Word that dragons nest in) to a ridiculous degree. I'm level 33, I've unlocked ~9 shouts, 3 of which have been upgraded to 2 words and 2 with 3, and I still have 4 souls left over. It's kinda ridiculous, to be perfectly honest.