instigator

/ˈɪnstɪɡeɪtər/
noun
  1. A person who causes something to happen, especially something negative or controversial.
    • She was known as the instigator of many office pranks.
    • The police arrested the instigator of the riot.
    • Historians debate who was the true instigator of the war.
Antonyms
What does "instigator" mean? | whatsthatwordmean | whatsthatwordmean