Frank Costello

"I don't want to be a product of my environment: I want my environment to be a product of me. Years ago, we had the church. That was only a way of saying "we had each other." The Knights of Columbus were real head-breakers, true guineas; they took over their piece of the city. Twenty years after an Irishman couldn't get a f-cking job, we had the presidency - may he rest in peace. That's what the n---ers don't realize. If I got one thing against the black chappies, it's this: no one gives it to you. You have to take it."

- Frank Costello's opening lines.

"See I got this rat - this annoying, cheating, f-cking rat. And it brings up questions... You know, see, Bill, like... you're the new guy. Girlfriend, hmmm, why did you stay in the bar that night I got you numbers?"

- Frank Costello talking to the film's protagonist, Billy Costigan, about one of his crew members being a police informant - not realizing that Costigan himself is the mole.

Frank Costello is a fictional character and the primary antagonist of the 2006 crime drama film The Departed.

History
Introducing the film in a prologue set several years before the events of the plot, Frank Costello happens to meet a 10-year-old by the name of Colin Sullivan while collecting protection money from a local convenience store. Taking a shine to the child, Costello gives Sullivan a huge supply of groceries (plus a comic book for good measure) and informs him that if he ever wants to earn a little extra he should look him up on L street. Soon after, Sullivan begins working for Costello, who introduces him to the criminal underworld and gradually molds him into his pawn in the legitimate world: as an adult, Sullivan joins the Massachusetts State Police, passing his exams with flying colors and eventually being accepted into the Special Investigations Unit, which focuses on organized crime. Here, he serves as Costello's mole, keeping him informed of developments within the Staties and manipulating the department to the crime lord's advantage.

Howver, unknown to both Costello and Sullivan, police trainee Billy Costigan is secretly recruited by Captain Queenan and Staff Sergeant Dignam to become an undercover agent. At their behest, Costigan drops out of the police academy, goes to prison on false charges, and is eventually able to earn membership in Costello's gang - but not before being brutally interrogated by a boot-wielding Costello.

As both infiltrate their respective organizations, Costello soon becomes the subject of a major investigation, as he has managed to obtain twenty weapons-grade microprocessors and is planning to sell them them to a Chinese syndicate. Thanks to Sullivan, however, Costello manages to escape the sting; in the process, both moles become aware of the other's existence, though not their respective identities. Sullivan is told to find the "rat" and asks Costello for his underlings' personal information (birth dates, Social Security numbers, etc.) to determine who is the informant within the crew; after tailing the crime lord to a porn theater - and getting flashed by Costello for good measure - Sullivan is finally given the details, only to end up getting tailed by Costigan in a chase through Boston's Chinatown district. When it is over, both men still do not know each other's identity.

Under Sullivan's guidance, Costello's gang ambushes a meeting between Queenan and Costigan, and though the police informer manages to escape with the captain's help, Queenan is caught by the gang and thrown to his death. During the resulting shootout between the gang and the police officers tailing them, one of Costello's minions, Delahunt, is mortally wounded and later dies - though not before discovering Costigan's true identity and asking him why he didn't "say anything." When henchman Fitzy blunders hiding the corpse, news reporters covering the story reveal that Delahunt was also an undercover police officer, but Costello berates the rest of his crew for believing this, knowing that the more likely explanation is that the police declared Delahunt an informant in an attempt to make Costello drop his guard and end his search for the mole.

Under intense scrutiny and unable to end Costigan's mission, Sullivan later learns of Costello's role as an informant for the FBI from Queenan's diary, and begins to worry that his old mentor might reveal his dual identity. Not long afterwards, Costello makes arrangements for a cocaine drop-off, but on their way, Sullivan calls and reveals that the police are tailing Costello's cars; despite his best efforts to persuade the crime lord that he doesn't need to attend the drop-off, the mole is met only with screamed demands that he "get rid of the fucking tail," and is forced to comply. Fed up with Costello's arrogance and no longer trusting him due to his FBI connections, Sullivan betrays him by convincing Ellerby to prepare a special ops ambush at the drop-off.

There, Costello and his crew are ambushed by the police; Mr. French and the rest of the crew are killed, while Costello himself is badly wounded upon getting shot. After fleeing from the scene, Costello is confronted by Sullivan in a nearby construction site. Costello admits to being an FBI informant, but denies telling his handlers anything about Sullivan, -claiming that he is like a son to him. Outraged, Sullivan mockingly demands if that was what the entire arrangement between the two of them was about. He further implies that Costello is sterile and incapable of fathering sons of his own ,despite "all the fucking". This provokes Costello to get angry enough to shoot Sullivan, only to end up firing at his bullet proof vest - right before Sullivan instinctively shoots him in the chest. Costello, fatally wounded, slumps backwards into the open scoop of a construction excavator. As he succumbs to his wounds, Costello belatedly fires one last gunshot - which prompts Sullivan to fire multiple gunshots at his dying criminal mentor, killing Costello at last.

Following Costello's death, his criminal reign upon Boston is finally brought to an end. However, Costello would later be avenged when Sullivan himself is killed by Dignam - who, along with Costigan, discovered Sullivan as Costello's mole shortly after the former's death. As a result, Costigan ends up getting killed when he sought to finish what he was groomed into doing in the first place.

Trivia

 * Frank Costello was based on Whitey Bulger, an infamous Irish-American mobster who was able to escape justice for many years due to his alliance with corrupt FBI agent John Connolly.
 * Costello was also inspired by Hon Sam, the main antagonist of Internal Affairs - upon which The Departed was based.