Paul Giamatti as Harvey Pekar

Hope Davis as Joyce Brabner

Judah Friedlander as Toby Radloff

James Urbaniak as Robert Crumb

Earl Billings as Mr. Boats

James McCaffrey as Fred

Maggie Moore as Alice Quinn

Vivienne Benesch as Lana

Daniel Tay as Young Harvey

Harvey Pekar as Real Harvey

Donal Logue as Stage Actor Harvey

Josh Hutcherson as Robin

Joyce Brabner as Joyce Brabner

Molly Shannon as Stage Actor Joyce

Toby Radloff as Toby Radloff

Eytan Mirsky as Guitarist

Joey Krajcar as Batman

Chris Ambrose as Superman

Cameron Carter as Green Lantern

Mary Faktor as Housewife

Madylin Sweeten as Danielle

Ebon Moss-Bachrach as MTV Director

David Letterman as Self (archive footage)

Kurt Loder as Self (archive footage)

Shari Springer Berman as Interviewer (voice)

Larry John Meyers as Throat Doctor

Barbara Brown as Nurse

Danny Hoch as Marty

Eli Ganias as Pahls

Sylvia Kauders as Old Jewish Lady

Rebecca Borger as Cashier

Nick Baxter as Mattress Guy #1

Allen Branstein as Mattress Guy #2

Dick Prochaska as WWII Patient

Charles Eduardos as Doctor

Robert Pulcini as Bob the Director

Bianca Santos as Counter Girl

Mike Rad as Rand

Amy K. Harmon as Cheery Waitress

Rob Grader as Stage Manager

Terrence Sullivan as Letterman Regular

Patrick Lafferty as Yuppie

Jesse Perez as Miguel

Jeff Peters as Talk Show Host

Ola Creston as PA #1

Robert J. Williams as Cancer Doctor

Jason Stevens as Letterman Regular (voice)

Todd Cummings as Talk Show Host (voice)