Legend has it that during the Black Plague, superstitious Europeans started killing cats. The idea was that witches had caused the plague and cats were disguised devils, serving as the witches’ “familiar spirits,” ergo killing them would hurt the witches and hopefully spare people from the disease.

Of course, and I say this with the smug benefit of 700 years of hindsight, this “solution” only made the problem worse. Without cats, there were no natural predators for rats, which spread the disease via their lice.