Yep. Cats and the Black Plague. Actually, they were a complicating factor for some. The Christians killed (primarily black) cats, as they deemed them helpers of the devil and therefor complicit in spreading the plague. The Jews, on the other side, kept cats to keep house and storage vermin-free. So the Christians thought the Jews were in league with the devil, so they killed them, too - at least that was one of the “reasons” for pogromes. And it is also a reason why there are way less black cats in Europe than colored ones. It is a crazy topic…
But even if they had not killed those cats, the Black Death would have come. Maybe it would have spread a tad slower, but not much.