I worked for four years in one of the largest companies in the US witnessed or experienced my own version of just about every horror story written here but there was one that always stuck out as particularly cruel and horrible.
I worked on a production support team that was partner to a 5-man team that did bug fixes and programmed patches. The bug team consisted of several high-paid, long-time company people with masters degrees in vague things like "computer science". Most of them were actually pretty talented guys, but they had become extremely complacent and lazy.
Enter "contractor guy" from another country who was here on work visa. He was a genius, worked extremely hard, was very nice, pretty much never made a mistake and never said no to anything he was asked to do, even if it wasn't his job.
In about a year, this guy was doing all the work of the 4 of the 5 full time employees. They would come in late, leave early, defer any questions to him. They had an on-call rotation but if you paged one of the other dudes during their week, somehow contractor guy still ended up being the one staying up until 2am fixing the problem with you.
After about a year, management decided not to renew contractor guy's contract, to, and I quote "light a fire under the *** of his team, so they don't think they can just rely on one person". That'll show them, hold on to your 5 useless employees and fire the guy doing all the work. He ended up having to go back to his country and he even spent 3 months documenting everything he did. The other 5 dudes could not even be bothered to read what he'd wrote and learn what he did.
Not long after, I left this company and started my own business; I just could not be a part of something like that.