Sean Archer

Sean Archer is the main protagonist of movie, Face/Off.

He is an FBI agent going on a hunt against his archenemy, the terrorist Castor Troy. This is because he killed his son (accidentally as he's aiming for Archer himself) while they're in a carnival. Although he has him arrested, he has to switch faces with him when the terrorist's brother, Pollux, is not going to talk where the bomb's location is.