The Departed is a 2006 American epic crime thriller film directed by Martin Scorsese and written by William Monahan. It is both a remake of the 2002 Hong Kong film Infernal Affairs and also loosely based on the real-life Boston Winter Hill Gang; the character Colin Sullivan is based on the corrupt FBI agent John Connolly, while the character Frank Costello is based on Irish-American gangster Whitey Bulger. The film stars Leonardo DiCaprio, Matt Damon, Jack Nicholson, and Mark Wahlberg, with Martin Sheen, Ray Winstone, Vera Farmiga, and Alec Baldwin in supporting roles. It was the second collaboration between DiCaprio and Wahlberg after their work on The Basketball Diaries in 1995.

The film takes place in Boston. Irish Mob boss Frank Costello (Nicholson) plants Colin Sullivan (Damon) as a rat within the Massachusetts State Police; simultaneously, the police assign undercover state trooper Billy Costigan (DiCaprio) to infiltrate Costello's crew. When both sides realize the situation, Sullivan and Costigan each attempt to discover the other's identity before they are found out.

The Departed was a critical and commercial success, and won several accolades, including four Oscars at the 79th Academy Awards: for Best Picture, Best Director, Best Adapted Screenplay, and Best Film Editing. It became Scorsese's first and, to date, only win for Best Director;[9] Wahlberg was also nominated for Best Supporting Actor. The film also received six nominations at the 64th Golden Globe Awards, six nominations at the 60th British Academy Film Awards, and two nominations at the 13th Screen Actors Guild Awards. DiCaprio was nominated for Golden Globe Award for Best Actor – Motion Picture Drama (also nominated that year in the same category for Blood Diamond), BAFTA Award for Best Actor in a Leading Role and Screen Actors Guild Award for Outstanding Performance by a Male Actor in a Supporting Role for his performance.