We had this older woman in our office who used to decide to subtly target everything anyone did wrong who was younger than her, she'd pick a person and just begin to pick away at them in an innocent way. Nobody could identify what she did all day long, and she was obviously very insecure because she was the oldest person in the department. She would decide to pick at you for months, until you finally fought back somehow, and then she'd pick a new target, ever so subtly. I was not good at handling myself in those situations back then so I just was miserable for months until I finally burst into tears at her for whatever she did that day, and that was a crude but effective method. She turned her guns on someone else who tried to handle it for a while, but then eventually went to HR and she got nailed to the wall and decided to retire.
Also had a manager I'm pretty sure was borderline sociopathic. I've never meant someone so dishonest, manipulative, and greedy in my life. She got told to quit or be fired after some major upper management changes, so she quit, got a new job, and apparently got walked out of it a bit later on, and now she actually works at my current job site with basically the McDonald's shift supervisor of jobs in this organization. I had to deal with her once over the phone a couple of years ago and she still sounds like a dog with its tongue hanging greedily out of its mouth.