| 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 |
| Dabney Coleman | Commodore Louis Kaestner |
| Greg Antonacci | Johnny Torrio |
| Danny Burstein | Lolly Steinman |
| Frank Crudele | Big Jim Colosimo |
| Dana Ivey | Mrs. McGarry |
| Peter McRobbie | Supervisor Elliot |
| Erik Weiner | Agent Sebso |
| Stephen DeRosa | Eddie Cantor |
| Joseph Sikora | Hans Schroeder
(as Joe Sikora) |
| Pearce Bunting | Bill McCoy |
| Johnnie Mae | Louanne |
| Billy Smith | Davey Murdoch |
| Jordan Gelber | Simon |
| Chase Coleman | Billy Winslow |
| Kevin Carolan | Boardwalk Barker |
| Chloe Harting | Showgirl on Boardwalk |
| Francesca Scorsese | Little Girl on Boardwalk |
| Tracy Middendorf | Babbette
(as Tracy Lynn Middendorf) |
| Victor Verhaeghe | Ward Boss Fleming |
| John Rue | Mayor Harry Bacharach |
| William Hill | Ward Boss O'Neill |
| Robert Clohessy | Alderman Jim Neary |
| Samuel Taylor | Paddy Ryan |
| Edward McGinty | Ward Boss Boyd |
| Curtis Shumaker | Ward Boss |
| Noel Wilson | Ward Boss |
| Scott Jaeck | Ward Boss |
| Vince Giordano | Bandleader |
| Loyita Chapel | Crying Wife |
| Allen Jared | Crying Husband |
| Connor Noon | Tommy Darmody |
| Brady Noon | Tommy Darmody |
| John Mainieri | Brighton Hotel Manager |
| Steve Witting | Funeral Director |
| Jeannette Gould | Funeral Attendee |
| Prudence Wright Holmes | Widow |
| Jeffrey Ware | Still Worker
(as Jeff Ware) |
| Lucy Gallina | Emily Schroeder |
| Josie Gallina | Emily Schroeder |
| Declan McTigue | Teddy Schroeder |
| Rory McTigue | Teddy Schroeder |
| George R. Sheffey | Traymore Hotel Concierge
(as George Sheffey) |
| Randy Neumann | Referee |
| Nic Novicki | Carl Heely
(as Nick Novicki) |
| Adam Mucci | Deputy Halloran |
| Charleigh E. Parker | Lady Jean |
| Joseph Riccobene | Frankie Yale |
| Jonathan Brody | Reporter |
| Anthony Aibel | Reporter
(uncredited) |
| Angela Anvil | Flower Girl
(uncredited) |
| Malin Bergman | Dead Girl on Slab
(uncredited) |
| Heather Ashley Chase | Dancer Jessie
(uncredited) |
| Heather Lynne Chasse | Dancer Jessica
(uncredited) |
| Casey Cipriani | Tart
(uncredited) |
| Blaise Corrigan | Fighting Moonshiner
(uncredited) |
| Zoë D'Amato | Babette's Guest
(uncredited) |
| Byrne Davis Jr. | Whiskey Whiskers
(uncredited) |
| Michael Dean | FBI Instructor #1
(uncredited) |
| Jessica DiGiovanni | Tart
(uncredited) |
| William T. Donovan | Waiter
(uncredited) |
| Deanna Dys | Dancer
(uncredited) |
| David Gable | Maître d'
(uncredited) |
| Roy William Gardner | Faro Dealer
(uncredited) |
| Christopher G Gates | Gangster
(uncredited) |
| William Glenn | Aristocrat at Bar
(uncredited) |
| Kelly Karavites | Federal Agent
(uncredited) |
| Sasha Kaye | Prohibition Lady
(uncredited) |
| Martin Klebba | Boxing Dwarf
(uncredited) |
| Kate Kuen | Tart
(uncredited) |
| Chloe Lenihan | Woman in Palmistry
(uncredited) |
| Raymond Mamrak | (uncredited) |
| Anne-Sophie Marie | Theater Attendee
(uncredited) |
| Charles Marleau | Young FBI Agent
(uncredited) |
| Peter Mintun | Nickelodeon Pianist
(uncredited) |
| Joe Moran | FBI Recruit
(uncredited) |
| Costa Nicolas | Rocko
(uncredited) |
| Eddie Noone | FBI Instructor
(uncredited) |
| Molly Parker | Nucky's Wife in photo
(uncredited) |
| Sam Platizky | FBI Cadet
(uncredited) |
| Georgina Ransley | Tart
(uncredited) |
| Matthew Ray | FBI Student
(uncredited) |
| Peter Riga | Hotel Guest
(uncredited) |
| Jason Roeser | Bartender at Babettes
(uncredited) |
| Bruce Sabath | Dancing Business Tycoon
(uncredited) |
| Ann Marie Seall | Upper-Class Babette
(uncredited) |
| Harry L. Seddon | Fisherman
(uncredited) |
| Jessica Swesey | Dancer
(uncredited) |
| Vladimir Troitsky | Photo Studio Owner
(uncredited) |
| Guy Veryzer | Reporter
(uncredited) |
| Alex Martinez Wallace | Valet
(uncredited) |