Michael Sheen

as Dr. Slavkin O'Hara

Toni Collette

as Patricia Herman

Jason Spevack

as Henry James Herman

Samantha Weinstein

as Audrey O'Hara

Melyssa Ade

as Kindergarten Teacher

Oprah Winfrey

as Oprah

Frank Moore

as Stan Herman

Paul Braunstein

as Dr. Gunther Flowers

Hannah Brigden

as Young Patricia Herman

Sarah Orenstein

as Mother Herman

Jamie Johnston

as Young Billy Herman

Mark MacDonald

as Tim Herman

Mickey MacDonald

as Tom Herman

Cameron Kennedy

as Jimmy Herman

Kate Hewlett

as Alice O'Hara

Kevin Hare

as Delivery Room Doctor

Austin Macdonald

as Brian the Bully

Mishu Vellani

as Miss Abda

Aaron Abrams

as Malcom's Dad / Nurse Stewart