Cast / Szereplők:

• James McAvoy as Robbie Turner, the son of the Tallis family housekeeper with a Cambridge education courtesy of his mother's employer. McAvoy, who had refused previous offers to work with Wright, was the director's first choice; producers met several actors for the role, including Jake Gyllenhaal,^[7] but McAvoy was the only one offered the part. He fitted Wright's bid for someone who "had the acting ability to take the audience with him on his personal and physical journey". McAvoy describes Robbie as one of the most difficult characters he has ever played, "because he's very straight-ahead".^[8]
• Keira Knightley as Cecilia Tallis, the elder of the two Tallis sisters. Originally intended to play 18-year-old Briony, Knightley was the first reported to have landed one of the starring roles in Atonement, having previously worked with Wright on the cinema adaptation of Jane Austen's Pride & Prejudice (2005).^[9] With the director and Knightley unable to agree over which character the actress should play, Wright finally decided on Cecilia "because she has none of that Elizabeth Bennet vibe."^[9] In preparing for her role, Knightley watched films from the 1930s and 1940s, such as Brief Encounter and In Which We Serve, to study the "naturalism" of the performance that Wright wanted in Atonement.^[8]
• Saoirse Ronan as Briony Tallis, aged 13: the younger Tallis sister and an aspiring novelist. 12-year-old newcomer Ronan was not cast until casting director Jina Jay came across her following many unsuccessful auditions around Britain. McEwan called her performance "remarkable": "She gives us thought processes right on-screen, even before she speaks, and conveys so much with her eyes."^[8] Ronan received an Academy Award nomination for Best Supporting Actress for her performance.
• Romola Garai as Briony, 18: Following Abbie Cornish's refusal, backing out due to scheduling conflicts with Elizabeth: The Golden Age (2007),^[10] she was obliged to adapt her performance's physicality to fit the appearance that had already been decided upon for Ronan and Redgrave. Garai spent much time with Ronan, watching footage of her to approximate the way the younger actress moved.^[8]
• Vanessa Redgrave as older Briony: Everyone's ideal to play the oldest Briony,^[8] Redgrave was the first approached (although she was not cast until Ronan had been found),^[11] and committed herself to the role after just one meeting with Wright. She, Ronan and Garai worked together with a voice coach to keep the character's timbre in a familiar range throughout the film.^[8]
• Brenda Blethyn as Grace Turner, Robbie's mother and the Tallis family housekeeper.
• Juno Temple as Lola Quincey, the visiting 15-year-old cousin of the Tallis siblings.
• Benedict Cumberbatch as Paul Marshall, Leon Tallis' visiting friend.
• Patrick Kennedy as Leon Tallis, the eldest of the Tallis siblings.
• Harriet Walter as Emily Tallis, the matriarch of the family. Both Emily Watson^[12] and Kristin Scott Thomas^[12] were approached to play the role of Emily Tallis before the role went to Walter.
• Peter Wight as Police Inspector
• Daniel Mays as Tommy Nettle, one of Robbie's brothers-in-arms.
• Nonso Anozie as Frank Mace, another fellow soldier.
• Gina McKee as Sister Drummond
• Jérémie Renier as Luc Cornet, a fatally wounded and brain damaged French soldier whom the 18-year-old Briony comforts on his deathbed.
• Michelle Duncan as Fiona Maguire