Disguise

Disguises are a key plot element in several Final Fantasy series titles. Unlike an alternate outfit, a disguise is not under the player's control. Rather, disguises appear frequently in a given story to convey an element of stealth or surprise.

Final Fantasy IV
At an unknown point in time prior to the opening, Cagnazzo kills the king of Baron, then assumes his likeness as a disguise. None suspect anything amiss until years later, when "the king" develops a lust for crystals. It is not known who initially discovers Cagnazzo's deception, only that several characters suspect as much. He reveals himself fully when Cecil returns to Baron as a Paladin.