Brad Pitt Almost Played Matt Damon’s Role in The Departed—Here’s Why He Passed

It’s nearly impossible to imagine anyone other than Leonardo DiCaprio and Matt Damon playing the iconic roles of Billy Costigan and Colin Sullivan in Martin Scorsese’s The Departed. Their on-screen chemistry, perfectly capturing the paranoia and tension between two men on opposite sides of the law, made the 2006 crime thriller a modern classic. But as it turns out, the film could have looked quite different—especially in the case of Damon’s character, Sullivan—had Brad Pitt not made a key decision to step aside.

Before The Departed came to fruition, it was Pitt who, alongside producing partner Brad Grey, bought the rights to the 2002 Hong Kong thriller Infernal Affairs, which served as the basis for the American remake. Pitt and Grey were instrumental in getting the project off the ground, bringing in William Monahan to pen the script, a decision that ultimately attracted Scorsese to the project. “I developed that for two and a half years,” Pitt revealed in a 2007 interview with Interview Magazine. “We fought for that movie, and then we got William Monahan on the script.”

Initially, Pitt was set to play Colin Sullivan, the morally ambiguous Boston mob rat, alongside DiCaprio, who would take on the role of Billy Costigan, the Massachusetts State Police mole. Both characters are intelligent, ambitious, and willing to do whatever it takes to rise through the ranks—yet they are worlds apart in their allegiances. Sullivan becomes a member of mob boss Frank Costello’s (Jack Nicholson) crew, while Costigan infiltrates the gang to feed information back to the police. Despite their shared ruthlessness, their worlds collide in an intense final showdown that defines the film’s dramatic conclusion.

However, as The Departed continued to develop, one significant issue arose: the age difference between Pitt and DiCaprio. At the time, Pitt was a decade older than DiCaprio, and although the actor had long been able to maintain a youthful appearance, he eventually realized that the role of Sullivan was better suited to a younger actor. “Once Scorsese became involved, I thought it would be better if they were younger guys that were just starting their lives, guys coming out of the academy, guys who were hungry,” Pitt explained. “I thought I was too old for it.”

Though Pitt bowed out of the role, he remained deeply involved with the film as a producer. His decision to step aside ultimately led to Damon being cast in the role of Sullivan, and the dynamic between Damon and DiCaprio became one of the standout elements of The Departed. The film would go on to win four Academy Awards, including Best Picture, but Pitt, despite his significant contributions, did not take home an Oscar for his producing role. That would come later in 2014, when he won his first Oscar as a producer of 12 Years a Slave.

Pitt’s experience with The Departed also marked the beginning of his relationship with Scorsese, though he has not yet starred in another film with the legendary director. While he eventually won an acting Oscar for his supporting role in Quentin Tarantino’s Once Upon a Time in Hollywood, many still wonder how The Departed would have turned out had Pitt taken on the role of Sullivan.

Looking back, it’s clear that the casting of Damon and DiCaprio was pivotal to the film’s success. However, the story of how Brad Pitt’s decision to step aside opened the door for a fresh dynamic on-screen is just another fascinating chapter in the making of one of the most beloved crime thrillers in modern cinema.