| Steve Buscemi | Enoch 'Nucky' Thompson |
| Kelly Macdonald | Margaret Thompson |
| Michael Shannon | Nelson Van Alden |
| Shea Whigham | Elias 'Eli' Thompson |
| Michael Stuhlbarg | Arnold Rothstein |
| Stephen Graham | Al Capone |
| Vincent Piazza | Lucky Luciano |
| Michael Kenneth Williams | Chalky White |
| Anthony Laciura | Eddie Kessler |
| Paul Sparks | Mickey Doyle |
| Jack Huston | Richard Harrow |
| Ron Livingston | Roy Phillips |
| Jeffrey Wright | Valentin Narcisse |
| Gretchen Mol | Gillian Darmody |
| Patricia Arquette | Sally Wheet |
| Ben Rosenfield | Willie Thompson |
| Erik LaRay Harvey | Dunn Purnsley |
| Andrew Howard | August Tucker |
| Fredric Lehne | Owney Madden |
| Sean Cullen | Carl Billings |
| Herbert Bennett | Mickey's Warehouse Guard 1 |
| Margot Bingham | Daughter Maitland |
| Pearce Bunting | Bill McCoy |
| Owen Campbell | Clayton |
| Josh Caras | Henry |
| Jake Woodbury Davis | Tip |
| Noel Dinneen | Mickey's Warehouse Guard 2 |
| Kayla Ferguson | Doris |
| Rae Gray | Claudia |
| Roe Hartrampf | Skeeter Walsh |
| Tyler Jones | Temple Student |
| Warren Kelley | David Hewson |
| Elizabeth Ward Land | Helen Hewson |
| Lakisha May | Narcisse's Secretary |
| David McElwee | Roger's Friend |
| Shane Nepveu | Flitch |
| Glenn Quentin | Bellhop |
| James Michael Reilly | Realtor |
| Sebastian Tillinger | Hubert McCready |
| Katherine Waterston | Emma Harrow |
| Norman Aaronson | Fleeced Deed Buyer |
| Brian G. Andersson | Club Patron |
| Allen Holloway | UNIA Member |
| Sam Klein | Tennis Player |
| Doris McCarthy | Tampa Hotel Guest |
| Lily Narbonne | Temple University Student |
| Lynsey Leigh Price | Kissing Couple #2 |
| Jon Douglas Rainey | Al Capone's henchman |
| Corey Parker Robinson | (uncredited) |
| Bob Roseman | Fitzy |
| Gerard Sullivan | Nucky's Bodyguard |