| Steve Buscemi | Enoch 'Nucky' Thompson |
| Kelly Macdonald | Margaret Thompson |
| Michael Shannon | Nelson Van Alden |
| Shea Whigham | Elias 'Eli' Thompson
(credit only) |
| Michael Stuhlbarg | Arnold Rothstein |
| Stephen Graham | Al Capone |
| Vincent Piazza | Lucky Luciano |
| Michael Kenneth Williams | Chalky White
(credit only) |
| Anthony Laciura | Eddie Kessler |
| Paul Sparks | Mickey Doyle |
| Jack Huston | Richard Harrow |
| Charlie Cox | Owen Sleater |
| Bobby Cannavale | Gyp Rosetti |
| Gretchen Mol | Gillian Darmody |
| William Forsythe | Manny Horvitz |
| Christopher McDonald | Harry Daugherty - US Attorney General |
| Anatol Yusef | Meyer Lansky |
| Greg Antonacci | Johnny Torrio |
| Meg Steedle | Lillian 'Billie' Kent
(as Meg Chambers Steedle) |
| Stephen DeRosa | Eddie Cantor |
| Kevin O'Rourke | Mayor Edward Bader |
| Victor Verhaeghe | County Treasurer Damien Fleming |
| Arron Shiver | Dean O'Banion |
| Patrick Kennedy | Dr. Douglas Mason |
| Michael Cumpsty | Father Ed Brennan |
| Glenn Fleshler | George Remus |
| Lucas Caleb Rooney | Rosetti's Man |
| John Harrington Bland | Scotty Gulliver - Faraday Irons Manager |
| Joe Caniano | Jake Guzik |
| Kevin Carolan | Boardwalk Barker |
| Rony Clanton | Butler |
| Jacob Clemente | Delivery Boy |
| Margaret Daly | Mrs. Landau |
| Anthony DeVito | Deuces Bouncer #1 |
| Emily Dorsch | Cornelia Predock |
| Richard Flight | Rosetti Thug #5 |
| Erin Fogel | Mary |
| Josie Gallina | Emily Schroeder |
| Lucy Gallina | Emily Schroeder |
| Jenna Gavigan | Evelyn - Artemis Club Girl |
| Steven Hauck | Mr. Pendergast |
| Matt Hobby | House Servant Phillip |
| Robin Hopkins | Housewife |
| Mike Houston | Ralph - Faraday Irons Salesman |
| Ed Jewett | Jess Smith |
| Robert C. Kirk | Mr. Johansen - Motorist |
| Matthew Lawler | Mr. Posner |
| Paul Locke | Rosetti Thug |
| Robin Madel | Prudence |
| Charlotte Maier | Intellectual Female Guest |
| Edward McGinty | Ward Boss Aloysius Boyd |
| Declan McTigue | Teddy Thompson |
| Rory McTigue | Teddy Thompson |
| John Mondin | Carny |
| Brady Noon | Tommy Darmody |
| Connor Noon | Tommy Darmody |
| Ned Noyes | Hank - Faraday Irons Salesman |
| Kerry O'Malley | Edwina Shearer |
| Jacqueline Pennewill | Lillian |
| Joseph Riccobene | Frankie Yale |
| Kate Cullen Roberts | Gossipy Prostitute |
| James Rutledge | Hospital Chairman |
| Suzanne Savoy | Mrs. Pendergast |
| Christiane Seidel | Sigrid Mueller |
| Yelena Shmulenson | Emma Horvitz |
| Nick Stannard | Board Dignitary 1
(as Nicholas Stannard) |
| Jeremiah Wiggins | Albert McCaully |
| Ryan Woodle | Phil - Faraday Irons Salesman |
| Nick Wyman | Dr. Landau |
| Lee Zarrett | Nate - Faraday Irons Salesman |
| Kiva Dawson | Party Dancer #1 |
| Carolyn Doherty | Party Dancer #2 |
| Deanna Dys | Party Dancer #3 |
| Tyler Ingram | Party Dancer #4 |
| Mark Manley | Party Dancer #5 |
| Manuel Palazzo | Party Dancer #6 |
| Felicity Stiverson | Party Dancer #7 |
| William Ward | Party Dancer #8 |
| Nick Diamantis | Rosetti Thug |
| Jacob Wingfield | Rosetti's thug |
| Anne Bergstedt | Prostitute
(uncredited) |
| Laura Butler | Egyptian Waitress
(uncredited) |
| David Campbell | Nucky's Bodyguard #1
(uncredited) |
| Joseph Dimartino | Four Deuces Bartender
(uncredited) |
| Risa Dorken | Lower Class Girl
(uncredited) |
| Tomas Elizondo | Chester
(uncredited) |
| Zeke Elizondo | Chester
(uncredited) |
| Ed Heavey | Nucky's Bodyguard #2
(uncredited) |
| David Itchkawitz | Upscale Citizen
(uncredited) |
| Kelly Karavites | The New Thompson House Butler
(uncredited) |
| Karmen Kluge | The New Thompson House Maid
(uncredited) |
| Steve Konopelski | Office Party Guest
(uncredited) |
| Paul Jude Letersky | Farraday's Salesman #4
(uncredited) |
| Frank L. Messina | Capone Bodyguard /
Torrio Bodyguard
(uncredited) |
| John Mitchell | Rosetti Thug #2
(uncredited) |
| Jena Mroz | Gillian's Prostitute
(uncredited) |
| Miriam Pultro | Artemis Club Girl
(uncredited) |
| Kelsey Saunders | Musician
(uncredited) |
| Tom Stratford | Rosetti Thug #4
(uncredited) |