I was leaving the Riverwood Trader and noticed Stump falling from the sky. After hitting the ground you guessed it, he died. Normally I've seen Mammoths do this, but never Stump.

I've had my horse do this. I had just fast travelled to one of the snowy parts of Skyrim, and I was about to move forward when a horse fell out of the sky, hit the floor and instantly died. I felt like I was in a 'Monty Python' sketch...