Corporate Wolves
They were having an affair at work. Another employee caught them making out at work and reported it to HR. The manager told HR she had caught the employee stealing, and she made up the story to protect herself. HR agreed with the manager, and fired the associate reporting the theft on the spot despite not having any proof.
She was caught with another subordinate two months later. HR did not take any action, as it would force them to admit they had fired the employee in error. It was bad enough that they promoted the manager into a vacant position in another department. After all of that, I quit the company.