I think I have been lucky in that most of my coworkers have been either very friendly or pretty neutral at the very least.

But there was this one old fat bitch I worked with who would just randomly try to start fights with people for no particular reason. No one seemed safe from her wrath with most people taking turns on the shit end of it. It would always catch me off guard when it happened and would honestly tend to make me rather upset. In between her episodes she seemed like a normal person though which was confusing. I'd imagine that and the fact that she had worked there forever also would have made it difficult for management to consider getting rid of her.

For context, I worked in a lab where I was handling blood and urine. One day I was minding my own business when she comes up to me and starts trying to start a fight for God knows what reason about something I can't remember. I had a container of urine with me and it took everything in me not to chuck it at her ugly face. But I knew that would just get me fired and possibly an assault charge. So I managed to grit my teeth and settle a bit.

Several years later and I'm now in a different, way better job making a ton more money than her sorry ass. So I guess I kind of win??