Leonardo DiCaprio

William 'Billy' Costigan, Jr.

Matt Damon

Staff Sgt. Colin Sullivan

Jack Nicholson

Francis 'Frank' Costello

Mark Wahlberg

Staff Sgt. Sean Dignam

Vera Farmiga

Dr. Madolyn Madden

Martin Sheen

Capt. Oliver Charles Queenan

Ray Winstone

Mr. Arnold 'Frenchy' French

Anthony Anderson

Trooper Brown

Alec Baldwin

Capt. George Ellerby

Kevin Corrigan

Cousin Sean

James Badge Dale

Barrigan

David O'Hara

Fitzy

Mark Rolston

Delahunt

Robert Wahlberg

Lazio (FBI)

Kristen Dalton

Gwen

Thomas B. Duffy

Govenor

Richard Hughes

Uncle Edward

J.C. MacKenzie

Realtor

Mary Klug

Billy's Aunt

Peg Holzemer

Mrs. Kennefick

Robert 'Toshi' Kar Yuen Chan

Triad Boss

Gurdeep Singh

Pakistani Proprietor

Armen Garo

Providence Gangster #1

John Cenatiempo

Providence Gangster #2

Joseph Riccobene

Kneecapped Bankrobber

Billy Smith

Detective #1 Tailing Queenan

Lyman Chen

Translator

Kevin P. McCarthy

Detective #1 - Colin's Unit

Chris Fischer

Detective #2 - Colin's Unit

Brian Smyj

Man Glassed in Bar

William Severs

Older Priest

Larry Mitchell

Younger Priest

Anthony Estrella

Police Camera Tech

Andrew Breving

Police Cell Phone Tech

Tracey Paleo

Darlene the Secretary

Douglas Crosby

Man Killed by French

Dorothy Lyman

Woman at Bar #1

Audrie Neenan

Woman at Bar #2

Frank Mallicoat

News Anchor

Paula DeMers

Billy's Mother

Conor Donovan

Young Colin

Amanda Lynch

Carmen

Sallie Toussaint

Woman at Opera

Patrick Coppola

Bookie Harassed by French

Mick O'Rourke

Jimmy Bags

Deborah Carlson

Sister Mary Theresa

Nellie Sciutto

Queenan's Secretary

Peter Welch

Other Prisoner

Henry Yuk

Chinese Government Man

Dennis Lynch

Costello's Crew #1

Michael Byron

Costello's Crew #2

William Lee

Costello's Crew #3

John Rue

Luncheonette Proprietor

Peter Crafts

Man in Costello's Bar

Joseph P. Reidy

Priest with Young Colin

John Farrer

Priest at Billy's Funeral

Paris Karounos

Jimmy Pappas

Brian Haley

Detective #2 Tailing Queenan

Terry Serpico

Detective #3 Tailing Queenan

Jay Giannone

Detective #4 Tailing Queenan

John Polce

Lynn Detective

Bo Cleary

Drill Instructor #2 (voice)

David Conley

Gang Member with Mr. French

Victor Chan

Chinese Delivery Man

Jill Brown

Executed Woman

Sarah Fearon

French's Wife

Denece Ryland

Woman Doctor

Zachary Pauliks

Young Billy

Daniel F. Risteen, Jr.

Crack House Cop #1

Francis P. Hughes

Crack House Cop #2

Johnny Cicco

Crack Addict

Chance Kelly

Exam Instructor

Shay Duffin

Bartender at Brasserie

John McConnell

Bookie in Costello's Bar

Kenneth Stoddard

State Trooper #1

Jeffrey Winter

State Trooper #2

Paddy Curran

New Guy

Mark Philip Patrick

New Guy

David Fischer

Executed Man

Walter Y.F. Wong

Waiter in Alley

Tony M. Yee

Waiter in Alley

Francesca Scorsese

Little Girl at Airport

Alex Morris

Young Man at Airport

Emma Tillinger Koskoff

Woman with Dog

Craig 'Radioman' Castaldo

Crack House Denizen

Takumi Bando

Triad (uncredited)

Eric Bruno Borgman

Reporter (uncredited)

Brendan Burke

Irish Thug (uncredited)

Chris Chinn

Gang Member (uncredited)

Jeffrey Corazzini

Crime Scene Unit (uncredited)

Jim Ford

Cadet (uncredited)

Trudi Goodman

Woman Office Worker (uncredited)

Steve Lord

Academy Pistol Coach (uncredited)

Jack McCullough

EMT (uncredited)

Osmani Rodriguez

Reporter (uncredited)

Lawrence Cameron Steele

Academy Firearms Instructor (uncredited)

Conor Timmis

Rugby Fan (uncredited)

Joseph Oliveira

Officer (uncredited)

Adam Masnyk

Southie Teen / Soccer Player (uncredited)

John Franchi

Pedestrian (uncredited)

Paul McGillicuddy

Subway Passenger (uncredited)

Kim Carrell

MA State Police Detective

Rebecca Love

Adult Film Actress (uncredited)