Leonardo DiCaprio (William 'Billy' Costigan), Matt Damon (Staff Sergeant Colin Sullivan), Jack Nicholson (Frank Costello), Mark Wahlberg (Staff Sergeant Bryce Dignam), Martin Sheen (Captain Oliver Queenan), Vera Farmiga (Madolyn Madden), Ray Winstone (Arnold French), Alec Baldwin (Captain George Ellerby), Anthony Anderson (Brown), James Badge Dale (Barrigan), Mark Rolston (Timothy Delahunt), David O'Hara (Fitzy), Kristen Dalton (Gwen), J.C. MacKenzie (Immobilienmakler), Kevin Corrigan (Cousin Sean), Robert Wahlberg (Lazio, FBI)