I'd forgotten about it until the third page but I also needed life support for breathing in the first week of life. So that's probably the closest to death, though it wasn't really to being killed.
The first answer that came to mind was when I found myself facing the wrong way on a highway after a friend had swerved to avoid an animal and ended up doing a 180 (soon followed by another 180). Fortunately traffic was very light, and we didn't end up crashing into anything. But it could have been quite bad with heavier traffic.
Another possibility is when I feel face-first from about 9 feet onto a gravel surface, almost exactly a year before the above experience. My first instinct then was to make sure I still had mobility in both arms and legs. It resulted in an unexpected afternoon at the dentist's the next day, but nothing serious and long-term.
The other contender was when I managed to bash my head open on a wall when I was one year old. I don't remember it, so I don't know how serious it was, but I still have a scar on my forehead from it.
I can't think of quite the adjective I want, but there have been many stories here that are some combination of sobering, serious, subdued (in atmosphere), and moving. Probably good that I don't plan to go to sleep right away.