Jacob Tremblay as Auggie

Julia Roberts as Isabel

Owen Wilson as Nate

Izabela Vidovic as Via

Noah Jupe as Jack Will

Millie Davis as Summer

Bryce Gheisar as Julian

Mandy Patinkin as Mr. Tushman

Danielle Rose Russell as Miranda

Daveed Diggs as Mr. Browne

Mark Dozlaw as Teenage Doctor

Rukiya Bernard as Nurse

Jennifer March as Neonatologist

Elle McKinnon as Charlotte

Ty Consiglio as Amos

Kyle Breitkopf as Miles

James A Hughes as Henry

J. Douglas Stewart as Darth Sidious

Ali Liebert as Ms. Petosa

Joseph Gordon as Dodgeball Player

Cameron Roberts as Cute Guy

Erika McKitrick as Ella

Nadji Jeter as Justin

Ben Immanuel as Mr. Davenport

Jason McKinnon as School Photographer

Izzy Lieberman as Reid

Hannah Hoberman as Rebecca

Michael Alan Healy as Chewbacca

Sônia Braga as Grans

Nicole Oliver as Jack Will's Mom

Emily Delahunty as Ximena Chin

Lucia Thain as Savanna

Sasha Neuhaus as Maya

Rachel Hayward as Miranda's Mom

Callahan Brebner as Guy on Bus

Caleb Gordon as Our Town Player

Grayson Maxwell Gurnsey as Our Town Player

Emily Giannozio as Our Town Player

Haley Goldin as Our Town Player

Maccie Margaret Chbosky as Via (Age 4)

Victoria V. Cruz as Science Fair Judge

Yan-Kay Crystal Lowe as Julian's Mom

Steve Bacic as Julian's Dad

Jason Tremblay as Camp Counsellor

William Dickinson as Eddie

Emma Tremblay as Michelle

Armen Bagdasarov as Danny

Lidya Jewett as Lina Annan

Kaelyn Breitkopf as Angela

Brayden Snow as Classmate (uncredited)

Andre Robinson as School Kid (uncredited)

Alyssa Andronyk as School Kid (uncredited)

Wilson Chieng as Simon Stimson (uncredited)

Dallas Snow as Classmate (uncredited)

Justin Snow as Classmate (uncredited)

Kayzhia Snow as Classmate (uncredited)

Amber Snow as Classmate Parent (uncredited)

Elayna Sing as Classmate (uncredited)

Ann Evans as Parent (uncredited)

Abigail Friend as Daughter at Coney Island Beach (uncredited)

Razvan Orban as Boy in Red (uncredited)

Kari Staten as Parent (uncredited)