I used to go ghost hunting in my early days, and whilst I've definitely heard things that can't be explained and always go in with my skeptic's hat on, there's only ever been one incident that I can't attribute to anything else.
It was about 15 years ago and around this time of year. I'd visited my then girlfriend and was on my way back home through the countryside and had plenty of long stretches of straight road so you could see what was coming and what was behind. It was pretty dark, would have been somewhere between 11 and midnight, and it was a route I used regularly at the time so knew the road. I was all alone on that stretch at this particular moment.
I was paying attention to what I was doing, as you would on a dark night where it isn't lit, when I came across a black figure in the road, right by the kerb on my side, I believe walking away from me. I had to swerve, as it came out of nowhere, and I remember hitting the brakes afterwards to see who/what it was, but there was no-one there. I'm certain it was a figure, tall and human shapred, right on the road. I don't think I had full beams on, which may have revealed them (whoever it may have been) earlier, but the fact that they were gone still gives me chills. I kept going as the whole thing had left me shocked. I don't think I even considered stopping, thinking back.
Granted, it could have been my mind playing tricks on me. I don't remember being particularly tired, as I had a significant drive from one place to the other (no more than 1 hour via my route). I distinctly remember the black shape, no other colour to it, and obviously it caught me off guard that late and that remotely.
It was roughly at
this spot on the A4260, so it could have been someone trudging along, but they were completely black, and I couldn't see them in my brake lights.