In line with the Arseholes Who've Ruined Groups And Hobbies thread.
I was reading the thread and realised I had more stories regarding workplaces than groups or hobbies.
Have you ever left a job you really enjoyed because of That One Person and what did they do? How bad was it?
I had HR lady who was so particular she bought the whole office matching cups & would threw out any personal mugs she came across (but lie and say it wasn't her) She was the same with photos or nic nacs on desks - She would wait till you left for the day and throw them away. Then totally deny it was her.
She also demanded we took of our shoes off on coming into the office and had to purchase a (flats only) dedicated 'indoors only' stay at the office pair.