Jake Gyllenhaal
Robert Graysmith
Robert Downey Jr.
Paul Avery
Anthony Edwards
Bill Armstrong
John Carroll Lynch
Arthur Leigh Allen
Elias Koteas
Jack Mulanax
Dermot Mulroney
Captain Martin Lee
John Terry
Charles Thieriot
Donal Logue
Captain Ken Narlow
Adam Goldberg
Duffy Jennings
Richmond Arquette
Zodiac 1 / Zodiac 2
June Diane Raphael
Mrs. Toschi
Ciara Hughes
Darlene Ferrin
Clea DuVall
Linda del Buono
Lee Norris
Young Mike Mageau
Jimmi Simpson
Mike Mageau
James Le Gros
Officer George Bawart
Philip Baker Hall
Sherwood Morrill
Patrick Scott Lewis
Bryan Hartnell
Pell James
Cecilia Shepard
Jason Wiles
Lab Tech Dagitz
Charles Schneider
Cabbie / Paul Stine
Doan Ly
Belli's Housekeeper
Joel Bissonnette
Inspector Kracke
John Mahon
Riverside Captain
Jules Bruff
Catherine Allen
J. Patrick McCormack
Police Commissioner
Charles Fleischer
Bob Vaughn
Paul Schulze
Sandy Panzarella
Penny Wallace
Mulanax's Secretary
John Hemphill
Donald Cheney
Michel Francoeur
Man on Marquee
Thomas Kopache
Copy Editor #1
Barry Livingston
Copy Editor #3
Christopher John Fields
Copy Editor #4
Stanley B. Herman
Staff Editor
Brett Rickaby
Detective Roy (uncredited)
Micah Sauers
David Graysmith (uncredited)
Hayati Akbas
Hardware Store Customer (uncredited)
David Winston Barge
Vallejo Desk Ofiicer (uncredited)
Geoff Callan
Patrolman Zelms (uncredited)
Brad Carr
Camera Man (uncredited)
JD Cullum
Director (uncredited)
Rod Damer
FBI Codebreaker (uncredited)
Judith Drake
Florence Douglas (uncredited)
Mitchell Fink
Reporter (uncredited)
Erica Ford
Traveler (uncredited)
Ted Garcia
Anchorman (uncredited)
Gloria Grant
Bettye Harden (uncredited)
Tish Hicks
Informant (uncredited)
Phoebe Holston
Prison Guard (uncredited)
Michael Hungerford
Truck Driver (uncredited)
Janis Jones
Police Receptionist (uncredited)
Roy Lee Jones
Distraught African American Male (uncredited)
Anna Katarina
Society Woman (uncredited)
Marty Lodge
Pinole Foreman (uncredited)
Danielle McKee
Prisoner (uncredited)
Cazimir Milostan
Internal Affairs Agent (uncredited)
Betty Murphy
Informant (uncredited)
Dave Nemeth
Newscaster (uncredited)
Derris Nile
Office Worker (uncredited)
James Joseph O'Neil
DOD Project Leader (uncredited)
Jeff Daniel Phillips
Informant (uncredited)
Carmen Plumb
Janie (uncredited)
Peter Quartaroli
Patrolman Fouke (uncredited)
Michael Rose
Navy Project Leader (uncredited)
Jack Samson
Young David Graysmith (uncredited)
Zachary Sauers
Aaron Graysmith (uncredited)
Bill Seward
TV News Anchor (uncredited)
Callie Thompson
Child Witness (uncredited)
Cooper Thornton
Internal Affairs Agent (uncredited)
Cassius Willis
Uniform Cop (uncredited)
Shane Woodson
Informant (uncredited)