I'm not sure if this qualifies as "supernatural," but I met someone who could only have been the REAL Santa Claus when I was four years old.
For real.
I grew up in Oakland, California, until just before my fourth birthday, when my parents divorced. My mother took my younger brother and I back to the small (really small!) town of Midway, Utah, where her parents lived. My birthday is December 11th, I had just turned four, and my Mother and Grandmother took me and my younger brother - still a toddler - up to "the city" (Salt Lake City, the only real metropolitan center in the entire state) one day to go Christmas shopping. They split up and I was with my grandmother - I found out years later they split up so Mom could get my presents, and grandmother would get my brother's presents.
While walking with grandma, I saw Santa Claus in the department store with Mrs. Claus, and a few other kids in line waiting to see them. I wanted to see them, too, or course, and grandma, being a softie, took me over.
As we got close, Mrs. Claus turned to us, looked down at me, and immediately said:
"Hi John. Where's Robert?"
Being four, that was a perfectly natural question for her to ask me, and I responded that he was over somewhere with Mom.
She smiled and said something nice, never once looking at my grandma.
(I still remember this very clearly; it's one of my strongest, early memories.)
As we got closer to ol' Santa himself, I waited for what seemed lime a long time for the "big kid" - an eight-year-old or-so girl - to get off Santa's lap.
When it was finally my turn, Santa Claus looked at me, recognized me, and (according to my grandmother years later) said something along the lines of how surprised he was to see me all the way out in Utah.
Again, as a four-year-old, it was only natural that Mr. And Mrs. Claus would know me, and show surprise that we were in Utah; I never questioned it, or even Santa's existence. Over the years that followed I would argue With my friends as they one-by-one stopped believing in him; ('of course he's real!’, I'd say: 'I met him!')
It wasn't until I was a sophomore in high school that one day I asked grandma about that experience. She thought for a minute, then her eyes widened as she remembered, and told me from her perspective what happened:
The Mr. and Mrs. Claus in the ZCMI department store in Salt Lake City one night of December 1968 not only knew me and that I had a brother, and that we had been living in a different state, they knew the names of EVERY child in that line.
I am not making this up.
According to my grandma, Mr. and Mrs. Claus knew every child ON SIGHT; they never so much as glanced that their accompanying parents. Grandma, and she said the other parents as well, were astonished that these two strangers knew their children. Neither my grandma nor any of the parents she saw recognized them. As she and approached them, she saw that they knew the children ahead of us (the reason the 'big kid' was taking so long on Santa's lap was because SHE was reasoning that since he knew her, she probably knew him, and would recognize him behind his beard - although according to grandma, the beard was real...), and grandma assumed they were a local couple who knew some of the local kids, but she about passed out when Mrs. Claus turned and spoke to me.
Again, on my honor, I am not making this up.