1. a person who provokes or initiates an action, especially trouble or conflict

Examples

• The police identified him as the main instigator of the riot.
• She was known as an instigator who always stirred up drama at work.
• The teacher quickly separated the instigator from the other students.
• He denied being the instigator of the fight between the two groups.
• The instigator of the protest was arrested for disturbing the peace.
• Parents complained that one child was the instigator of all the playground conflicts.