I'm so grateful to have never been in a serious accident. I've taken plenty of spills on the trails, but nothing worse than a few bruises or scratches here and there. I've never come close in traffic either, which I think is mostly luck mixed with the fact that I'm an extremely defensive rider when on the road.
One guy I ride with got in a collision on a fire access road coming down a mountain though. It was a steep grade, all loose rocks and gravel, and thick forest on either side. He's about three quarters of the way down and just booting it, I don't know how fast but probably close to 20km/hr. Anyway, a deer jumps out onto the road, without warning the way they like to, maybe two feet in front of my buddy. He jams on the brakes, starts skidding and takes out the deer. Luckily he was wearing a helmet with full face coverage, because I'm pretty sure those flailing hooves could have done a lot of damage.
Anyway, man and deer untangled themselves and the deer hopped away into the forest and my friend came out of it shaken up but with a good story... I'm left just hoping that I never have to witness an accident that's more serious than funny.