| Steve Buscemi | Enoch 'Nucky' Thompson |
| Michael Pitt | James 'Jimmy' Darmody |
| Kelly Macdonald | Margaret Schroeder |
| Michael Shannon | Nelson Van Alden |
| Shea Whigham | Elias 'Eli' Thompson |
| Aleksa Palladino | Angela Darmody |
| Michael Stuhlbarg | Arnold Rothstein |
| Stephen Graham | Al Capone |
| Vincent Piazza | Lucky Luciano |
| Paz de la Huerta | Lucy Danziger |
| Michael Kenneth Williams | Chalky White |
| Anthony Laciura | Eddie Kessler |
| Paul Sparks | Mickey Doyle |
| Jack Huston | Richard Harrow |
| Gretchen Mol | Gillian Darmody |
| Dabney Coleman | Commodore Louis Kaestner |
| Charlie Cox | Owen Sleater |
| William Forsythe | Manny Horvitz |
| Enid Graham | Rose Van Alden |
| Chris Mulkey | Boss Frank Hague |
| Jennifer Ferrin | Carolyn Rothstein |
| Kevin O'Rourke | Edward Bader |
| Victor Verhaeghe | Ward Boss Fleming |
| Anatol Yusef | Meyer Lansky |
| Sidné Anderson | Demanding Mother |
| Joseph Aniska | Agent Sawicki |
| Marilyn Sue Perry | Mrs. Mayhew |
| Joel Brady | Agent Clarkson |
| Pearce Bunting | Bill McCoy |
| Justiin A. Davis | Lester White |
| Lucy Gallina | Emily Schroeder |
| Josie Gallina | Emily Schroeder |
| Devin Harjes | Jack Dempsey |
| Kevin Henderson | Dr. Carl Surran |
| Tyrone Mitchell Henderson | Wilfred |
| Christina Jackson | Maybelle White |
| Skai Jackson | Adeline White |
| John Keating | Ernie Moran |
| Rege Lewis | Travis Elkins |
| Heather Lind | Katy |
| Declan McTigue | Teddy Schroeder |
| Rory McTigue | Teddy Schroeder |
| Nneoma Nkuku | Aphra Tyson |
| Brady Noon | Tommy Darmody |
| Connor Noon | Tommy Darmody |
| Jacqueline Pennewill | Lillian |
| Ty Robinson | Samuel Crawford |
| Bill Sage | Solomon Bishop |
| Sol Landerman | Herman Kaufman |
| Megan Sikora | Dominatrix |
| Franklin Ojeda Smith | Deacon Lemuel Cuffy |
| Peter Van Wagner | Isaac Ginsburg |
| Natalie Wachen | Lenore White |
| Amy Warren | Pauline |
| Linda Thompson Williams | Widow |
| DeWanda Wise | Henny Walker |
| Michael Zegen | Benny Siegel |
| Ian Bonner | Working Class Thug |
| J.J. Pyle | Prostitute #3 |
| Tom Stratford | Townsman |