Milo Coy

Stan

Jack Black

Grown Up Stan (voice)

Lee Eddy

Mom

Bill Wise

Dad

Natalie L'Amoreaux

Vicky

Josh Wiggins

Steve

Jessica Brynn Cohen

Jana

Sam Chipman

Greg

Danielle Guilbot

Stephanie

Zachary Levi

Kranz

Glen Powell

Bostick

Larry Jack Dotson

Grandfather

Mona Lee Fultz

Grandmother #1

Jennifer Griffin

Grandmother #2

Holt Boggs

Sam The Rocket Man

Reese Armstrong

Tony

Natalie Joy

Music Class Teacher

Suzanne Deal Booth

Science Teacher

Chris Olson

Principal Cowan

Samuel Davis

Pinball Buyer

Mia Gonzalez

Statue-Maker Kid

Brian Villalobos

Bales

Chris Zurcher

Jack

Alex Fink

Kid on Astroway

Zia Kinzy

Young Lady on Astroway

David DeLao

Mr. St. George

Noah Randall

Drive-In Employee

Athena Wintle

Mindy

Xavier Patterson

Emanuel

Nick Stevenson

SIMSUP

William Carroll

Abominable Snowman

Avery Joy Davis

Lisa (uncredited)

Christian Moran

Hoodlum (uncredited)

Nicholas Andrew Rice

NASA Controlman (uncredited)

Keslee Blalock

AstroWorld Kid (uncredited)

Brent A. Riggs

Service Station Attendant (uncredited)

P. Michael Hayes II

SIMSUP (uncredited)

Flint Nattinger

Laughing Boy (uncredited)