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

Zach Galifianakis

Kevin

Steven Wiig

Lee's Ferry Ranger

Cheryl Francis Harrington

Social Worker

R. D. Call

Bull

Haley Ramm

Carine McCandless (age 11)

Merritt Wever

Lori

John Jabaley

Announcer

Leonard Knight

Leonard Knight

J. Nathan Simmons

Tourist (uncredited)

Haley Sweet

Bank Teller (uncredited)

Bart the Bear II

Bear