persecutor

/ˈpɜːrsɪˌkjuːtər/
noun
  1. A person who treats someone cruelly or unfairly, especially because of their beliefs, race, or identity.
    • The dictator was known as a brutal persecutor of political opponents.
    • Many refugees fled their country to get away from their persecutors.
    • In the story, the hero escapes from his persecutor and finds safety in a new land.