Johnny Depp

James 'Whitey' Bulger

Joel Edgerton

John Connolly

Julianne Nicholson

Marianne Connolly

Dakota Johnson

Lindsey Cyr

Kevin Bacon

FBI Agent Charles McGuire

Benedict Cumberbatch

Billy Bulger

Peter Sarsgaard

Brian Halloran

Juno Temple

Deborah Hussey

Jesse Plemons

Kevin Weeks

David Harbour

John Morris

Adam Scott

FBI Agent Robert Fitzpatrick

Corey Stoll

Fred Wyshak

W. Earl Brown

John Martorano

Bill Camp

John Callahan

Mark Mahoney

Mickey Maloney

Brad Carter

John McIntyre

Scott G. Anderson

Tommy King

Lonnie Farmer

DEA Agent Eric Olsen (Interrogator)

Mary Klug

Mom Bulger

Erica McDermott

Mary Bulger

Luke Ryan

Douglas Cyr

Owen Burke

Buddy Leonard

Lewis D. Wheeler

Jeremiah O'Sullivan

Billy Meleady

Joe Cahill

Jamie Donnelly

Mrs. Cody

David De Beck

Roger Wheeler

Gary Galone

State Captain

Rory Cochrane

Stephen Flemmi

James Russo

Agent Scott Gariola

Jeremy Strong

Josh Bond

Danae Nason

McGuire's Secretary

Bretton Manley

Young Boy

Berglind Jonsdottir

Anna Bjornsdottir

Robert Walsh

Sr. FBI Official (voice)

David Conley

Officer Flynn

Ciaran Crawford

Irish Nationalist

Thomas Philip O'Neill

FBI Wire Tech

Joey Vacchio

Joey, Big Italian

Bill Haims

Gennaro Angiulo

Anthony Molinari

Charlie McTiernan

Declan Mulvey

Charlie's Friend

Bates Wilder

Agent James

Marc Carver

Dick Lehr

Richard Donelly

Gerard O'Neill

Brian A. White

Prisoner

Peter Morse

FBI Agent

Tom Kemp

Father Mackey

Patrick M. Walsh

Michael Donahue

Naheem Garcia

DEA Agent

Kathryn A. Beauchamp

Nurse

Stephen Curran

Drug Dealer

Darin X.L. MacEachern

Drug Dealer

Cary 'Big Shug' Guy

Drug Dealer

Sean Malone

Crook

Jack Neary

Barman

Jimmy Joe Maher

Boot Shop Owner

Forry Buckingham

World Jai Alai Chairman

Danny DeMiller

Porthole Bartender

Michael F. Murphy

Porthole Customer

Alexander Cook

DEA Agent Dan Doherty

Ava Cooper

Little Mary Bulger

Stella Cooper

Kathleen Bulger

Arthur Hiou

Driver

Todd Ryan Jones

Charlie's Friend

Julie Ann Dawson

Floor Dancer (uncredited)

Fergaledgar

Trevor Williams (uncredited)

Jim Powers

The Mayor

Robert Walsh

Sr. FBI Official (voice)

Jeff Kamps

Walker

Susan Garibotto

Press Photographer

Colleen Kelly

Marion Hussey (uncredited)