 | Johnny Depp als James 'Whitey' Bulger |
 | Joel Edgerton als John Connolly |
 | Julianne Nicholson als Marianne Connolly |
 | Dakota Johnson als Lindsey Cyr |
 | Kevin Bacon als FBI Agent Charles McGuire |
 | Benedict Cumberbatch als Billy Bulger |
 | Peter Sarsgaard als Brian Halloran |
 | Juno Temple als Deborah Hussey |
 | Jesse Plemons als Kevin Weeks |
 | David Harbour als John Morris |
 | Adam Scott als FBI Agent Robert Fitzpatrick |
 | Corey Stoll als Fred Wyshak |
 | Bill Camp als John Callahan |
 | Mark Mahoney als Mickey Maloney |
 | Brad Carter als John McIntyre |
 | Scott G. Anderson als Tommy King |
 | Lonnie Farmer als DEA Agent Eric Olsen (Interrogator) |
| Mary Klug als Mom Bulger |
 | Erica McDermott als Mary Bulger |
| Luke Ryan als Douglas Cyr |
 | Owen Burke als Buddy Leonard |
 | Lewis D. Wheeler als Jeremiah O'Sullivan |
| Billy Meleady als Joe Cahill |
 | Jamie Donnelly als Mrs. Cody |
 | David De Beck als Roger Wheeler |
 | Gary Galone als State Captain |
 | Rory Cochrane als Stephen Flemmi |
 | James Russo als Agent Scott Gariola |
 | Jeremy Strong als Josh Bond |
 | Danae Nason als McGuire's Secretary |
| Bretton Manley als Young Boy |
| Berglind Jonsdottir als Anna Bjornsdottir |
| David Conley als Officer Flynn |
| Ciaran Crawford als Irish Nationalist |
 | Thomas Philip O'Neill als FBI Wire Tech |
| Joey Vacchio als Joey, Big Italian |
| Bill Haims als Gennaro Angiulo |
 | Anthony Molinari als Charlie McTiernan |
 | Declan Mulvey als Charlie's Friend |
 | Bates Wilder als Agent James |
| Marc Carver als Dick Lehr |
| Richard Donelly als Gerard O'Neill |
 | Brian A. White als Prisoner |
| Peter Morse als FBI Agent |
 | Tom Kemp als Father Mackey |
 | Patrick M. Walsh als Michael Donahue |
 | Naheem Garcia als DEA Agent |
| Kathryn A. Beauchamp als Nurse |
| Stephen Curran als Drug Dealer |
| Darin X.L. MacEachern als Drug Dealer |
 | Cary 'Big Shug' Guy als Drug Dealer |
| Sean Malone als Crook |
 | Jack Neary als Barman |
| Jimmy Joe Maher als Boot Shop Owner |
| Forry Buckingham als World Jai Alai Chairman |
| Danny DeMiller als Porthole Bartender |
| Michael F. Murphy als Porthole Customer |
| Alexander Cook als DEA Agent Dan Doherty |
| Ava Cooper als Little Mary Bulger |
| Stella Cooper als Kathleen Bulger |
 | Arthur Hiou als Driver |
| Todd Ryan Jones als Charlie's Friend |
| Julie Ann Dawson als Floor Dancer (uncredited) |
| Fergaledgar als Trevor Williams (uncredited) |
 | Robert Walsh als Sr. FBI Official (voice) |
 | W. Earl Brown als John Martorano |
 | Jim Powers als The Mayor |
 | Jeff Kamps als Walker |
 | Susan Garfield als Press Photographer |
| Mark A. Mangini | Supervising Sound Editor |
| Mark A. Mangini | Sound Re-Recording Mixer |
| Francine Maisler | Casting |
| Claire Simpson | Additional Editing |
| Ezra Dweck | Sound Editor |
| Ron Bartlett | Sound Re-Recording Mixer |
| Romulo Adriano Jr. | Visual Effects Coordinator |
| David Rosenbloom | Editor |
| Goro Koyama | Foley Artist |
| Andy Malcolm | Foley Artist |
| Jez Butterworth | Screenplay |
| Brett Ratner | Executive Producer |
| Tracey A. Doyle | Set Decoration |
| Tom Holkenborg | Original Music Composer |
| Brian Oliver | Producer |
| Patrick McCormick | Producer |
| Patrick McCormick | Unit Production Manager |
| Stefania Cella | Production Design |
| Richard Mirisch | Associate Producer |
| Scott Cooper | Director |
| Scott Cooper | Producer |
| Morris Flam | Gaffer |
| Morris Flam | Chief Lighting Technician |
| Joel Harlow | Makeup Department Head |
| Don White | Foley Mixer |
| Carla Meyer | Dialect Coach |
| Masanobu Takayanagi | Director of Photography |
| Masanobu Takayanagi | Camera Operator |
| Tyler Thompson | Producer |
| Steve Buscaino | Prosthetic Supervisor |
| Chuck Jeffreys | Stunt Coordinator |
| Phil Hunt | Executive Producer |
| Compton Ross | Executive Producer |
| Kyle Cooper | Title Designer |
| Michael Bassick | Co-Executive Producer |
| Kasia Walicka Maimone | Costume Design |
| Sarah Contant | Assistant Art Director |
| John Lesher | Producer |
| Christopher Woodrow | Executive Producer |
| Adam Kassan | Co-Executive Producer |
| Christos Michaels | Legal Services |
| Lucia Mace | Key Hair Stylist |
| Jeremy Woodward | Art Direction |
| Mark Mallouk | Screenplay |
| Virginia B. Johnson | Costume Supervisor |
| Joseph Kearney | Construction Coordinator |
| James Packer | Executive Producer |
| Piero Mura | Sound Effects Editor |
| Judson Bell | Special Effects Coordinator |
| Chris Jenkins | Sound Re-Recording Mixer |
| Ken Niederbaumer | Key Makeup Artist |
| Jim Schultz | Music Editor |
| Allison Paul | Visual Effects Producer |
| Ann Scibelli | Sound Designer |
| Tim LeDoux | Visual Effects |
| Jason Sanford | Visual Effects |
| Katrina Schiller | Supervising Music Editor |
| Howard Samuelsohn | Dialect Coach |
| Claire Folger | Still Photographer |
| Beau Desmond | Costumer |
| David B. Nowell | Aerial Director of Photography |
| Erik Rogers | Digital Intermediate Producer |
| John Polyson | Visual Effects Editor |
| David Gulick | Property Master |
| Matthew W. Johnson | Digital Conform Editor |
| Henry Tirl | Camera Operator |
| Henry Tirl | Steadicam Operator |
| Charles Harrington | Location Manager |
| Gloria Pasqua Casny | Hair Department Head |
| Spooky Stevens | Unit Publicist |
| Lauren Selig | Executive Producer |
| Don Libby | CG Supervisor |
| Scott D. Davis | Rigging Gaffer |
| Robert 'Rock' Galotti | Armorer |
| Brett Granstaff | Executive Producer |
| Ben Bornstein | Key Makeup Artist |
| Tracy Scott | Script Supervisor |
| Steven Mnuchin | Executive Producer |
| Jill Brown | Stunts |
| Bryan Felty | Set Designer |
| Gary Granstaff | Executive Producer |
| Peter Mallouk | Executive Producer |
| Ray Mallouk | Executive Producer |
| Woody Bell | Key Rigging Grip |
| Khanh Trance | Wigmaker |
| Chris Navarro | ADR Mixer |
| Maili Lafayette | Costumer |
| Philippe Majdalani | Digital Intermediate Producer |
| Jason Mayoh | Art Department Coordinator |
| Jonny Winograd | First Assistant Editor |
| Rita Troy | Hairstylist |
| Tom Williams | Sound Mixer |
| James W. Apted | First Assistant Camera |
| Gerard O'Neill | Book |
| Dick Lehr | Book |
| Byron Wilson | Supervising Sound Editor |
| Steven Wayne | Production Supervisor |
| Xanthus Valan | Second Assistant Director |
| Donald Burghardt | First Assistant Camera |
| Michele Ziegler | First Assistant Director |
| Melissa Kostenbauder | Casting Associate |
| Mark Coffey | First Assistant Sound Editor |
| Brittany Loar | Assistant Costume Designer |
| Paul Linden | Visual Effects Supervisor |
| Matt Bouldry | Casting Associate |
| Taryn Walsh | Costumer |
| Greg Wimer | First Assistant Camera |
| Nikki Pleau | Makeup Artist |
| Riley Fearon | Art Department Assistant |
| Cesha Ventre | Costumer |
| Chris LeDoux | Visual Effects |
| Bobby Anderson | Picture Car Coordinator |
| Tish Johnson | Production Accountant |
| Dana Pacheco | Costumer |
| Elizabeth Clifford | Costumer |
| Chuck Rock | Co-Executive Producer |
| Joel Reidy | Boom Operator |
| Steve Brennan | Assistant Property Master |
| Benjamin C. Dewey | Location Manager |
| Thomas J. O'Connell | ADR Mixer |
| David Bleich | Matte Painter |
| Julia Correnti | Compositor |
| Michael Peterson | Assistant Chief Lighting Technician |
| Joe Rosenbloom | Assistant Editor |
| Tom Poole | Senior Colorist |
| Jack Heeren | Foley Mixer |
| Dieter Hartmann | Music Programmer |
| Noah Dubreuil | Assistant Property Master |
| Zack Shultz | Second Assistant Camera |
| Robert Knowles | Best Boy Grip |
| Derek Contrado | Rigging Grip |
| Laura Brocato | Visual Effects Coordinator |
| Tony Pilkington | Mixing Engineer |
| Wilson Gallego | Prop Maker |
| Joe Gagnepain | Set Dresser |
| Timothy M. Sweeney | Second Assistant Camera |
| Erik Werlin | Visual Effects |
| Ana Criado-Zahonero | Title Designer |
| Don Hewitt Sr. | Stunts |
| Clinton E. O'Dell | Costumer |
| Frank A. Montesanto | Key Grip |
| Dean Egan | Second Assistant Camera |
| Alex Falcon | CG Artist |
| Joanna Raskin | Hairstylist |
| Hannah Scott | Stunts |
| Tony Campenni | Dolly Grip |
| Robert Schleinig | Leadman |
| Thomas Doran | Dolly Grip |
| Leighana Ginther | Compositor |
| Rebecca DiFillippo | Production Secretary |
| Zachary Zablocki | Prop Maker |
| Jason Coffey | Carpenter |
| Christina Todesco | Set Designer |
| Joseph E. Doyle | 24 Frame Playback |
| Brendan Tierney | Lighting Technician |
| Ewelina Nietupska | Digital Intermediate |
| Ani Vanoyan | Second Assistant Accountant |
| Maria Palazon | Travel Coordinator |
| Kevin Samar | Compositor |
| Alex Hatfield | Digital Compositor |
| Mark Stern | Visual Effects |
| Timothy Blockburger | Second Second Assistant Director |
