Hmmm. Once, I was trying out a supposed "kid horse" that a friend of my Dad's was thinking about buying for his daughters. Since I had a lot more experience, they wanted me to ride him around first. My brother and I were riding around town, loping down a back road when the horse saw something off to his right that he spooked at. He sucked back and to the left and I came off. It shattered my left arm and I got to spend my entire summer break with 4 screws, 1 pin, and an external fixator on my arm.
Most recently, I was breaking an older mare to ride. I got her saddled up with no issues but when I asked her to move out away from me, she blew up and went to bucking. She turned toward me and started heading my way and even though I tried to get out of her way while driving her back, I was too slow. She shouldered into me in the middle of a buck and knocked me into the fence. I ended up having to get 7 stitches to close up the gigantic gash in my forehead from slamming it into one of the rungs on the fence.
There are quite a few others, but those are the first ones to pop into my mind.