James McAvoy as Dennis / Patricia / Hedwig / The Beast / Kevin Wendell Crumb / Barry / Orwell / Jade

Anya Taylor-Joy as Casey Cooke

Betty Buckley as Dr. Karen Fletcher

Haley Lu Richardson as Claire Benoit

Jessica Sula as Marcia

Izzie Coffey as Five-Year-Old Casey

Brad William Henke as Uncle John

Sebastian Arcelus as Casey's Father

Neal Huff as Mr. Benoit

Ukee Washington as News Anchor

Ann Wood as Game Show Enthusiast

Robert Michael Kelly as Joe

M. Night Shyamalan as Jai, Hooters Lover

Rosemary Howard as Kevin's Mother

Jerome Gallman as Vince, Security Guard

Lyne Renee as Academic Moderator

Kate Jacoby as Dr. Fletcher's Patient

Peter Patrikios as Taxi Driver

Kash Goins as Flower Kiosk Worker

Roy James Wilson as Security Guy with Dog

Christopher Lee Philips as Older Worker

Julie Potter as Paramedic

Ameerah Briggs as Police Officer #1

Nakia Dillard as Police Officer #2

Robin Rieger as Television Reporter

Emlyn McFarland as Diner Waitress

Dann Fink as Game Show Contestant (voice)

Bruce Winant as Game Show Host (voice)

Bruce Willis as David Dunn (uncredited)

Kim Director as Hannah (uncredited)

Robert Bizik as Bar Patron (uncredited)

Junnie Lopez as Geraldo (uncredited)

Steven Dennis as Dan at Next Table (uncredited)

Matthew Nadu as Waiter (uncredited)

James Robinson Jr. as Claire's Party Guest (uncredited)

John Mitchell as EMT (uncredited)

Aleksandra Svetlichnaya as Pedestrian (uncredited)

Colin Campbell as Boy in Park (uncredited)

John Jillard Sr. as Homeland Security (uncredited)

Vincent Riviezzo as Detective (uncredited)

Gary Ayash as Restaurant Patron (uncredited)