In European folklore, which supernatural entities assisted witches in their practice of magic?

The black cat with a witch is portrayed most often.

These ridiculous beliefs have led to the mistreatment of many black cats and delay in them being adopted from shelters. Really, is there any excuse for these silly superstitions in this day and age?

Kiwozzie, Even Sabrina had Salem.

Catweazle had a familiar. Google that show.