https://en.wikipedia.org/wiki/La_Voisin
Catherine Monvoisin, or Montvoisin, née Deshayes, known as "La Voisin" (c. 1640 – 22 February 1680), was a French fortune teller, commissioned poisoner, and professional provider of alleged sorcery. She was the head of a network of fortune tellers in Paris providing poison, aphrodisiacs, abortion, purported magical services and the arranging of black masses, with clients among the aristocracy, and became the central figure in the famous affaire des poisons. Her purported organization of commissioned black magic and poison murder was suspected to have killed 1,000 people, but it is believed that upwards of 2,500 people might have been murdered.[1]