| 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 |
| Charlie Cox | Owen Sleater |
| Bobby Cannavale | Gyp Rosetti |
| Gretchen Mol | Gillian Darmody |
| Stephen Root | Gaston Means - Special Investigator |
| Julianne Nicholson | Assistant US Attorney Esther Randolph |
| Christopher McDonald | US Attorney General Harry Daugherty |
| Meg Steedle | Lillian 'Billie' Kent |
| Billy Magnussen | Roger McAllister |
| Heather Lind | Katy |
| Glenn Fleshler | George Remus - Bootlegger |
| Peter Appel | Alby Gold |
| Mark Borkowski | Paul Sagorsky |
| Marc D. Donovan | Deputy Ramsey - Tabor Heights |
| Emily Dorsch | Cornelia Predock - Thompson Neighbor |
| Tim Eliot | Matthews - Disabled WWI Veteran |
| Alice Ellis | Gwynne - Artemis Club Girl |
| Tod Engle | Bribing Lobbyist 2 |
| Jack Ferry | Thompson House Guard Gareth Murray |
| William Fowle | Bribing Lobbyist 3 |
| Josie Gallina | Emily Schroeder |
| Lucy Gallina | Emily Schroeder |
| John Hemphill | |
| Matt Hobby | Thompson House Butler Phillip |
| Ed Jewett | Jess Smith - Daugherty's Aide |
| Jeff Kready | World War One Veteran |
| T.J. Linnard | Tuckman WWI Veteran |
| Robin Madel | Thompson House Servant Prudence |
| Graeme Malcolm | |
| Neal Matarazzo | |
| Declan McTigue | Teddy Thompson |
| Rory McTigue | Teddy Thompson |
| Bruce Meakem | |
| Susan Louise O'Connor | Hotel Maid |
| Greg Peace | Federal Guard |
| Jacqueline Pennewill | Thompson House Maid Lillian |
| Steve Routman | Davidoff |
| Wrenn Schmidt | Julia Sagorsky |
| Jim Schubin | Phil Gardner |
| Tighe Swanson | Fire Breather |
| Jeff Talbott | Boy Scout Troop Leader |
| Katherine Waterston | Emma Harrow |
| Alex Webb | Bribing Lobbyist 1 |
| Brendan Abbott | World War One Veteran |
| Chris Angerman | Newsboy |
| Gary Craig | Political Lobbyist |
| David Itchkawitz | Upscale Citizen |
| Josh Pesin | World War I Veteran |
| Alexander Ryan | Boy Scout |
| Will Sandoval | World War I Veteran |
| Casey Smith | Fight Patron |
| Atdhe Trepca | Boy Scout |
| Kristopher Lee Weaver | Leroy Bradford Wendover |
| Jim Zunt | Courtroom Attorney |