Joaquin Phoenix

Arthur Fleck

Lady Gaga

Lee Quinzel

Brendan Gleeson

Jackie Sullivan

Catherine Keener

Maryanne Stewart

Zazie Beetz

Sophie Dumond

Steve Coogan

Paddy Meyers

Harry Lawtey

Harvey Dent

Leigh Gill

Gary Puddles

Ken Leung

Dr. Victor Liu

Jacob Lofland

Ricky Meline

Bill Smitrovich

Judge Herman Rothwax

Sharon Washington

Debra Kane

Alfred Rubin Thompson

Ernie Bullock

Connor Storrie

Young Inmate

Gregg Daniel

Music Teacher

Mac Brandt

Arkham Guard

George Carroll

Arkham Guard

John Lacy

Arkham Guard

Tim Dillon

Arkham Guard

Wayne Dehart

E Ward Inmate

Jimmy Walker Jr.

E Ward Inmate

Toney Wilson

E Ward Inmate

June Carryl

Dr. Louise Beatty

Don McManus

Paddy Meyers' Producer

G.L. McQueary

Head Bailiff

Angela D. Watson

Jury Foreman

Murphy Guyer

White Chapel Minister

Carson Higgins

Junior Associate

Gattlin Griffith

Masked Joker Driver

Hudson Oz

Joker Doppelganger

Ray Lykins

Victim's Dad

Will Ropp

Joker Fan #1

Ashton Moio

Joker Fan #2

Brian Donahue

Additional Guard

Mike Houston

Additional Guard

Jess King

Additional Guard

Jimmy Smagula

Additional Guard

Stephen Stanton

Stan L. Brooks (voice)

Martin Kildare

News Anchor

Laurie Dawn

Reporter

Dominiqué Williams-Blair

Reporter

Barry Bonder

Reporter

Kaylah Sharve' Baker

Back-up Singer

Ashley Levin

Back-up Singer

Celeste Butler

Back-up Singer

Casey Burke

Girl #1 (uncredited)

Troy Metcalf

Music Room Inmate #1 (uncredited)

Ben van Diepen

Music Class (uncredited)

Karen Teliha

B Ward Music Class Patient #14 (uncredited)