David Lightman
Dr. Niko Tatopoulos
Phillipe Gaston
Richard Feynman
Sam
Clark Kellogg
Despereaux (voice)
Adam McMullen
Michael McPhae
Self
William Lightbody
Adam Flayman (voice)
Hubble (voice)
Simba (voice)
Professor Harold Hill
Charles MacArthur
Alan Simon
Jim McAllister
Steven Schats
Bruce
Ben Green
Tack the Cobbler (voice)
Steve Finch
Ferris Bueller
Taylor Peters
Col. Robert Gould Shaw
Walter Kresby
Steven M. Kovacs
Ben Singer
Roger Beekman
Leo Bloom
Cooper
Brian Everett
John Andrew van Tassel
Jimmy Garrett
Eugene Morris Jerome
Hally
Himself
Mr. Fitzhugh
Commentator
Brother
Bill Campbell
Self (archive footage)
Levar Mathis
Laird Becker
John Brown / Inspector Gadget / Robo Gadget
Self (archive footage) (uncredited)
Les Moore
Reader
Borden Chase
Murray Krafft
Matthew Broderick
John
June's Dad (voice)
Jeffrey Garner
Prince Henry
Himself (uncredited)
Ferris Bueller (uncredited)
Ralphie as an Adult
Albert
Narrator
Mr. Buellerton (uncredited)
Doug
Michael Woods
Mark (voice)
Talking Cat (voice)
Cooter Burger
Self - Guest
Self - Panelist
Self - William Swain
Self - Presenter
Self - Host
Dr. David Miller
Richard Sackler
John Ordway (voice)
Himself - Narrator (voice)
Peter
Max
Michael Burr
Dave
Joseph Sugarman (voice)
Self - Cameo (uncredited)
Jack Binns (voice)
Dream Warrior