Jacob Tremblay

Character: Auggie

Julia Roberts

Character: Isabel

Owen Wilson

Character: Nate

Izabela Vidovic

Character: Via

Noah Jupe

Character: Jack Will

Millie Davis

Character: Summer

Bryce Gheisar

Character: Julian

Mandy Patinkin

Character: Mr. Tushman

Danielle Rose Russell

Character: Miranda

Daveed Diggs

Character: Mr. Browne

Mark Dozlaw

Character: Teenage Doctor

Rukiya Bernard

Character: Nurse

Jennifer March

Character: Neonatologist

Elle McKinnon

Character: Charlotte

Ty Consiglio

Character: Amos

Kyle Breitkopf

Character: Miles

James A Hughes

Character: Henry

J. Douglas Stewart

Character: Darth Sidious

Ali Liebert

Character: Ms. Petosa

Joseph Gordon

Character: Dodgeball Player

Cameron Roberts

Character: Cute Guy

Erika McKitrick

Character: Ella

Nadji Jeter

Character: Justin

Ben Immanuel

Character: Mr. Davenport

Jason McKinnon

Character: School Photographer

Izzy Lieberman

Character: Reid

Hannah Hoberman

Character: Rebecca

Michael Alan Healy

Character: Chewbacca

Sônia Braga

Character: Grans

Nicole Oliver

Character: Jack Will's Mom

Emily Delahunty

Character: Ximena Chin

Lucia Thain

Character: Savanna

Sasha Neuhaus

Character: Maya

Rachel Hayward

Character: Miranda's Mom

Callahan Brebner

Character: Guy on Bus

Caleb Gordon

Character: Our Town Player

Grayson Maxwell Gurnsey

Character: Our Town Player

Emily Giannozio

Character: Our Town Player

Haley Goldin

Character: Our Town Player

Maccie Margaret Chbosky

Character: Via (Age 4)

Victoria V. Cruz

Character: Science Fair Judge

Yan-Kay Crystal Lowe

Character: Julian's Mom

Steve Bacic

Character: Julian's Dad

Jason Tremblay

Character: Camp Counsellor

William Dickinson

Character: Eddie

Emma Tremblay

Character: Michelle

Armen Bagdasarov

Character: Danny

Lidya Jewett

Character: Lina Annan

Kaelyn Breitkopf

Character: Angela

Brayden Snow

Character: Classmate (uncredited)

Andre Robinson

Character: School Kid (uncredited)

Alyssa Andronyk

Character: School Kid (uncredited)

Wilson Chieng

Character: Simon Stimson (uncredited)

Dallas Snow

Character: Classmate (uncredited)

Justin Snow

Character: Classmate (uncredited)

Kayzhia Snow

Character: Classmate (uncredited)

Amber Snow

Character: Classmate Parent (uncredited)

Elayna Sing

Character: Classmate (uncredited)

Ann Evans

Character: Parent (uncredited)

Abigail Friend

Character: Daughter at Coney Island Beach (uncredited)

Razvan Orban

Character: Boy in Red (uncredited)

Kari Staten

Character: Parent (uncredited)