A childhood belief about monsters

When I was 3 or 4, my mother told me about Santa Claus and how he came down the chimney. But I always imagined a monster, known only as "Fireplace Man" coming down the chimney. He had the ability to be invisible, shape shift, and walk on ceilings. He looked like a gray troll and had a ragged brown shirt. I had a number of nightmares about him. Thankfully, though, in one of the nightmares, my sister helped me push a boulder onto his head. I don't believe this anymore (duh) but I still have the occasional nightmare about him...