Almost got fired once when a close colleague spread rumors to put her failures on me. I never got to know precisely what she said but it was "extremely bad" and in the realm of harassment (not sexual, but still...).

The management was not sure and did not involve HR to make it formal. I felt under scrutiny for a while, so I kept all the communication to a minimum, strictly professional, not even an emoji or a joke about the weather, all in writing when possible and including other people every time it was possible. It was horrible and stressful. I considered to quit or to ask to be moved since interacting with her was part of a daily routine, but I feared that it could be seen as an admission of guilt.

Eventually she was fired in a round of layoffs and that was the end of it. Later I discovered from some colleagues that they never believed that shit, but nobody stepped in to say anything.