This isn't really a fear, but I don't want to be killed by anyone/anything. The only things that I will be okay with killing me is either myself or natural causes.
Now, fears. Being crushed is probably the worst for me. I don't know how it works, but I'm guessing that I would feel all my bones crack at once, and that just sounds outright painful. Plus, I'd still be conscious enough to feel it before I go, and I don't want that at all.
Another is being chopped/pulled apart. I want my body to be in-tact/in one piece when I die.
My final fear would probably be beheading. There's something so disturbing about beheading. It's like, the now-headless corpse was once a sentient being that could talk and think and is now nothing. That's so ♥♥♥♥ed up. I wouldn't wish a beheading on anyone.