Oh I have remembered some more...
The seat sniffer. Came back from lunch and caught him on his knees sniffing my chair. He said to me "I think you're ovulating." 
I used to work for someone who was very disorganised and used to sit on papers which needed a quick turnaround. One of my colleagues said one day, "I've had enough, I'm going to sort him out once and for all." Said colleague was slightly unhinged, so we thought this would be interesting and followed him down the corridor. He burst into boss's office shouting "If you don't sign off that pile of papers I'm going to fuck you up the arse, good and hard, right here over your posh desk." The office was full of some Arab businessmen who had come for a meeting.
But we got all the papers back signed, within half an hour of them leaving.
DH used to work somewhere which had squash courts and a gym in the basement, with the men's and women's showers and changing rooms next door to each other. A memo went round to all staff, saying it had been discovered that "someone" had drilled a hole in the wall between the two, and had been caught watching women in the shower. But not to worry, the hole had now been blocked up.
DH had a phantom crapper in his last office too! There is someone in mine who seems to manage to smear the back of the seat with poo. I don't think it's deliberate, I just think she is a bit lax in the wiping department.