Black cats were commonly thought to be familiars of witches.
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Familiars are animal spirits that come from the devil and are given to witches or sorcerers as a gift. Familiars are universally known, described in several different cultures around the world. It helps the witch by assisting with the casting spells, performing magical quests, or causing a human sickness and death. It only obeys the one witch or sorcerer and will not listen to anybody else. The witch will feed the familiars with blood through her fingers, thumb, or breast. The markings on the body made by the sucking familiars were known as “witches marks.” These animals were commonly cats, dogs, mice, birds, or toads.