Black cats are also symbols of Halloween and have religious origins as
well. Black cats were considered to be reincarnated beings with the ability to
divine the future. During the Middle Ages it was believed that witches could
turn themselves into black cats. Thus when such a cat was seen, it was
considered to be a witch in disguise. All these are popular trick-or-treat
costumes and decorations for greeting cards and windows.
Black is one of the traditional Halloween colors, probably because
Halloween festivals and traditions took place at night.