Formal:
* Un fauteur de troubles: This is the most literal translation and means "a troublemaker."
* Un agitateur: This means "an agitator" and implies someone who stirs up trouble.
* Un perturbateur: This means "a disruptor" and emphasizes the negative impact of the troublemaker's actions.
Informal:
* Un casse-cou: This means "a daredevil" and implies someone who gets into trouble through recklessness.
* Un filou: This means "a rascal" and suggests someone who is mischievous but not necessarily malicious.
* Un briseur de règles: This means "a rule-breaker" and emphasizes the troublemaker's disregard for rules.
* Un malandrin: This means "a rogue" and suggests a more serious troublemaker with a criminal element.
The best translation for "troublemaker" will depend on the specific context.