Tim Allen

Jason Nesmith

Sigourney Weaver

Gwen DeMarco

Alan Rickman

Alexander Dane

Tony Shalhoub

Fred Kwan

Sam Rockwell

Guy Fleegman

Daryl Mitchell

Tommy Webber

Enrico Colantoni

Mathesar

Robin Sachs

Sarris

Jed Rees

Teb

Justin Long

Brandon

Missi Pyle

Laliari

Patrick Breen

Quellek

Jeremy Howard

Kyle

Sam Lloyd

Neru

Rainn Wilson

Lahnk

J.P. Manoux

Excited Alien

Dian Bachar

Nervous Tech

Heidi Swedberg

Brandon's Mom

Kevin McDonald

Announcer (as Kevin Hamilton McDonald)

Kaitlin Cullum

Katelyn

Jonathan Feyer

Hollister

Corbin Bleu

Young Tommy

Isaac C. Singleton, Jr.

Sarris' Guard

Joel McKinnon Miller

Warrior Alien

Todd Giebenhain

Teen in the Bathroom #2

Jerry Penacoli

Reporter

Jennifer Manley

Shy Girl

Matt Winston

Technician #1

Morgan Rusler

Fan #2

David Dorfman

Boy (uncredited)

Susan Egan

Teek