One of my first wreck dives, probably my deepest, farther than I was certified at around 100', I saw one of these.
After checking out the wreck, I went back up the wrong line (wrong end of the wreck), simple mistake, but it was kinda lonely. About the last third, I noticed the guy hanging about 15 feet off, just sitting there staring at me. Since you have to take time ascending, so many feet/minute, it seemed like forever.
He never charged me or anything, but man was it eerie. He was basically motionless and obviously watching me, and me alone. I was glad to get out of the water, and never used the wrong line again.