Brent Swancer at Mysterious Universe write about real life encounters with Santa. Even while acknowledging that no such thing can happen, because Santa isn’t real, people experiencing such episodes know that something very real indeed happened.
While not experiencing a Santa sighting, I did have the following experience as a child, which I wrote about on my Saucer Sightings blog. It could be I was experiencing a simple case of childlike wonder and excitement at Santa and his reindeer, but at the same time, I was also experiencing a lot of UFO/alien activity at the time. Who can say, who knows?