Attacus is a mark in Final Fantasy XIII. One of the nine Undying, it is accessed via a third Cie'th Stone in the D stages after every stage of the fal'Cie Titan has been cleared in the Faultwarrens. Attacus is fought in "Mission 51". Titan creates a Behemoth King for the final task, but Attacus appears and slays the Behemoth King, afterward turning on the party.