X Marks the Death
Many people out there, including us, The Departed is one of Martin Scorsese’s best films to date. It’s not just about the action since there was actually very little of it. How the protagonist and antagonist managed to infiltrate each other’s organizations and feed info to their bosses was pure magic.
If you paid careful attention, you might have noticed several Xs in the backdrop. Apparently, every character that had an X behind or near them on screen would die later on. Several Xs appear for Billy Costigan and Colin Sullivan throughout the film. As for Barrigan, Frank Costello, and Oliver Queenan, they only appear almost immediately before their deaths.