Emile Hirsch
Christopher McCandless / Alexander Supertramp

Marcia Gay Harden
Billie McCandless

William Hurt
Walt McCandless

Jena Malone
Carine McCandless / Additional Narration (voice)

Brian H. Dierker
Rainey

Catherine Keener
Jan Burres

Vince Vaughn
Wayne Westerberg

Kristen Stewart
Tracy Tatro

Hal Holbrook
Ronald "Ron" Franz

Thure Lindhardt
Mads

Signe Egholm Olsen
Sonja

Jim Gallien
Jim Gallien

James J. O'Neill
Graduation Reader

Malinda McCollum
Waitress

Paul Knauls
Building Manager

Zach Galifianakis
Kevin

Craig Mutsch
Wayne's Crew #1

Jim Beidler
Wayne's Crew #2

John Decker
Hutterite #1

John Hofer
Hutterite #2

Jerry Hofer
Hutterite #3

Terry Waldner
Hutterite #4

Robin Mathews
Gail Borah

Candice Campos
Bar Girl

Steven Wiig
Lee's Ferry Ranger

Floyd Wall
Man In Phone Booth

Bryce Walters
Christopher McCandless (age 4)

Jim Davis
Immigration Officer

Cheryl Francis Harrington
Social Worker

R. D. Call
Bull

Haley Ramm
Carine McCandless (age 11)

Merritt Wever
Lori

Everett 'Insane Wayne' Smith
Insane Cain

John Jabaley
Announcer

Leonard Knight
Leonard Knight

Matt Contreras
Book Shopper #1

Denise Sitton
Book Shopper #2

Sharon Olds
Additional Narration (voice)

Carine McCandless
Additional Narration (voice)

J. Nathan Simmons
Tourist (uncredited)

Parris Mosteller
Young Boy (voice) (uncredited)

Timothy Levine
Atlanta Braves fan (uncredited)

Haley Sweet
Bank Teller (uncredited)

Aaron Wayne Hill
Big Wheel Boy (uncredited)

Bart the Bear II
Bear