A black cat and the number 13 are both associated with superstition, particularly in Western cultures.
Black cat: Often associated with bad luck when crossing your path, stemming from medieval associations with witches and evil spirits. In some cultures, such as Japan and the UK, black cats are considered lucky. They can also symbolize mystery and independence.
Number 13: Fear of 13 is called triskaidekaphobia, possibly originating from the Last Supper. Many Western cultures consider it unlucky, reflected in the absence of a 13th floor in some buildings. In other cultures, 13 is considered lucky.
Together, they are often seen as a potent symbol of misfortune in Western contexts, though meanings vary by individual perspective and cultural background.