Yup I have heard of it, still I do believe it is related to the shadow people phenomenon and not just one entity, I have seen shadow people as I described above, and non have had a hat.
Also, can you describe some of these experiences? Sound very interesting o.o
What it says on the title. Mine was when I was 12 and I lived in a very haunted house which had some weird activity going on, like things moving out of place and pets freaking out. I was sitting in the computer, alone in the house, and suddenly I see a shadowy figure on the screen, just some meters away behind me, thinking was my mom I turned around and there was nothing, but the room had turned extremely cold suddenly. There was nothing behind me that could have been this shadow.