Obviously loosing loved ones is high on or top of the list, for me and most of us I suspect.
I lost both parents, mom was a few years ago. I still miss her but wasn't traumatized, it was her time to go and she'd had a good life. In the natural order of things, parents go first.
the thing I would find hard, would be loosing my daughter. I was a single parent before I got married and then have 2 stepdaughters. Now I have 6 granddaughters, and loosing any of them would be tramatic.
Other than that, scary movies scare the shit out of me. I don't do horror movies. I saw Jaws on its first run in theatres, when that shark first came out of the water, I jumped so high I hurt my back on landing.