President

The big gun, big wheel, bigwig, boss, captain, chieftain, commander, dictator, director, duke, foreman, general, governor, head, head man, honcho, key player, king, leader, lord, manager, master, monarch, ogema, overlord, overseer, prince, principal, proprietor, ringleader, ruler, sovereign, superintendent, supervisor, top brass

Basically, the persion in charge!!