le chef, le leader
He is the leader of the factory's Red Guards.
Il est le chef des Gardes rouges de l’usine.
— To Live (1994)
Le chef de la bande.
Tu es le chef.
Who is the leader of this organization?
Qui est le dirigeant de cette organisation ?
— The Legend of Bhagat Singh (2002)
Martino became the leader.
Martino devint le chef.