Oh, man, I had a co-worker like that. Was my boss for a little while.
It is the most awful situation to be stuck in. He was good, too - everything he did was so low-key that complaining about it would have sounded totally idiotic.
He got clumsier when he became my supervisor. Eventually the situation became so obviously disruptive that I was reassigned - and fortunately for me, there was one supervisor who was sensitive enough to tone to pick up that something strange was going on - but I don't think anybody ever really understood the extent - once I was out from under him that was the main thing. Still, it's all in my personnel records & I still have occasional nightmares that I get to work one day & he's there, grinning the way he would grin as he sat there cheerfully cutting me down to size behind a closed door...
Has nothing to do with my usual subjects but brrr, what a shudder reading that.
Fortunately he's long gone. There were points where I really thought I was going to either quit or get fired, but I did stick it out & it's so much better now. Amazing what a few changes in staff can do for a department.