| Steve Buscemi | Enoch 'Nucky' Thompson |
| Kelly Macdonald | Margaret Thompson
(credit only) |
| Michael Shannon | Nelson Van Alden
(credit only) |
| Shea Whigham | Elias 'Eli' Thompson |
| Michael Stuhlbarg | Arnold Rothstein
(credit only) |
| Stephen Graham | Al Capone |
| Vincent Piazza | Lucky Luciano |
| Michael Kenneth Williams | Chalky White |
| Anthony Laciura | Eddie Kessler |
| Paul Sparks | Mickey Doyle
(credit only) |
| Jack Huston | Richard Harrow |
| Charlie Cox | Owen Sleater
(credit only) |
| Bobby Cannavale | Gyp Rosetti |
| Gretchen Mol | Gillian Darmody |
| Anatol Yusef | Meyer Lansky |
| Erik LaRay Harvey | Dunn Purnsley |
| Ty Robinson | Samuel Crawford
(as Ty Michael Robinson) |
| Nick Wyman | Dr. Landau |
| Chris Caldovino | Tonino Sandrelli |
| Kevin Csolak | William Thompson |
| Craig DiFrancia | Rosetti Soldier #6
(as Craig Di Francia) |
| Jack Ferry | Gareth Murray |
| Jason Furlani | Caiozzo |
| Anthony J. Gallo | Sam Moceri
(as Anthony Gallo) |
| Paul Locke | Rosetti Thug |
| Kate Loprest | Corrine |
| Karl Baker Olson | |
| Brady Noon | Tommy Darmody |
| Connor Noon | Tommy Darmody |
| Rocco Parente | Rosetti Thug #3
(as Rocco Parente Jr.) |
| Pat Vecchio | |
| KC Wright | Josephine |
| David Antoine | Mechanic
(uncredited) |
| Santana Draper | Chicken Bone Beach Kid
(uncredited) |
| Theodore Feldman | Hospital Visitor w /
Crutches
(uncredited) |
| Steve Fogelman | Hotel Doorman
(uncredited) |
| Noah Forrest | Capone Thug
(uncredited) |
| David Itchkawitz | Upscale Citizen
(uncredited) |
| Sean LeeRoy | Nucky's Bodyguard
(uncredited) |
| George Pendill | Gyp's Thug
(uncredited) |
| Kent Sladyk | Gangster
(uncredited) |