A hint of the uncanny on the Appalachian trail: A Walk in the Woods by Bill Bryson (1999)

....We walked for a week and hardly saw a soul. One afternoon I met a man who had been section hiking for twenty-five years with a bicycle and a car. Each morning he would drop the bike at a finishing point ten miles or so down the trail, drive the car back to the start, hike between the two and cycle back to his car. He did this for two weeks every April and figured he had about another twenty years to go. Another day I followed an older man, lean and rangy, who looked to be well into his seventies. He had a small, old-fashioned day pack of tawny canvas and moved with extraordinary swiftness. Two or three times an hour I would sight him just ahead, fifty or sixty yards away, vanishing into the trees. Though he moved much faster than I did and never seemed to rest, he was always there. Wherever there was fifty or sixty yards of view, there he would be—just the back of him, just disappearing. It was like following a ghost. I tried to catch up and couldn't. He never looked at me that I could see, but I was sure he was aware of me behind him. You get a kind of sixth sense for the presence of others in the woods, and when you realize people are near, you always pause to let them catch up, just to exchange pleasantries and say hello and maybe find out if anyone has heard a weather forecast. But the man ahead never paused, never varied his pace, never looked back. In the late afternoon he vanished and I never saw him again.

Bill Bryson, A Walk in the Woods (1999).