Ezra Miller as Robert

Jeremy Allen White as Dave

Emory Cohen as Trevor

Michael Stuhlbarg as Mr. Burke

Rosemarie DeWitt as Miss Vogel

Addison Timlin as Amy

David Costabile as Mr. Anderson

Dariusz M. Uczkowski as Peter

Gary Wilmes as Mr. Virgil

Lee Wilkof as Mr. Wiseman

Paul Sparks as Detective Eclisse

Bill Raymond as Mr. Williams

Alexandra Neil as Gloria Talbert

Mark Zeisler as Tom Talbert

Christopher McCann as Mr. Ullman

Byrdie Bell as Cherry Dee

Mary Michelson as Talbert Twin

Carly Michelson as Talbert Twin

Rebecca Boughton as Broken Glass Girl 1

Anna Maliere as Broken Glass Girl 2

Dani Baum as Broken Glass Girl 3

Julian Branciforte as Freshman Student

Marta Miller as Robert's Mom (voice)

Annette Foisy as Nurse

Paige Billings as AV Class Girl

Tony Costagliola as Senior Druggie

Cameron Ward as Boys Dorm Head

Richard White as Dave's Dad in Car

Christopher Brisson as Security Guard

Mackenzie Deary as Chapel Student

Will Child as Chapel Teacher

Javier Alvarez as Math Teacher

Ephraim Adamz as Screaming Senior

Robert Malitsky as Screaming Senior

Robert M. Saunders as Screaming Senior

Andrew Corkin as Screaming Senior

Laura Boucher as Robert's Memorial Video

Rosamund Dunn as Robert's Memorial Video

Timothy Dreary as Robert's Memorial Video

Mike Thomas as Robert's Memorial Video

Emily Potrezeba as Robert's Memorial Video

Paul Kramarz as Robert's Memorial Video

Jacob Allard as School Memorial Video

Amber Allard as School Memorial Video

Kristiana Sumera as School Memorial Video

Brittney Roy as School Memorial Video

Chloe Bates as School Memorial Video

Allyse Rosen as School Memorial Video

John Basnight as Student

Catie Botting as Student

Beckam Cela as Student

Alex Labeef as Student

Harrison Lees as Student

Colin Sebastian as Student