Black cats have played a major role in folklore, superstition, and mythology for centuries. In the middle ages, they were believed to be witches' incarnate or witches' familiar, the latter of which is an animal-shaped spirit or demon thought to serve a witch or magician as a spy and companion. Strangely, many of these old superstitions still exist to this day. Around Halloween. I adore black cats. I have had one cat, my dearly departed Starrbooty who was a lovely all sleek black cat. If I ever get another cat, I think it would have to be a black one. I think they are good luck in my opinion.