Bill Skarsgård as Pennywise

James McAvoy as Bill Denbrough

Jessica Chastain as Beverly Marsh

Bill Hader as Richie Tozier

Isaiah Mustafa as Mike Hanlon

Jay Ryan as Ben Hanscom

James Ransone as Eddie Kaspbrak

Teach Grant as Henry Bowers

Andy Bean as Stanley Uris

Joan Gregson as Mrs. Kersh

Jackson Robert Scott as Dead Georgie

Jaeden Martell as Young Bill Denbrough

Sophia Lillis as Young Beverly Marsh

Finn Wolfhard as Young Richie Tozier

Chosen Jacobs as Young Mike Hanlon

Wyatt Oleff as Young Stanley Uris

Jeremy Ray Taylor as Young Ben Hanscom

Jack Dylan Grazer as Young Eddie Kaspbrak

Nicholas Hamilton as Young Henry Bowers

Molly Atkinson as Myra / Sonia Kaspbrak

Luke Roessler as Dean

Javier Botet as Hobo / The Witch

Xavier Dolan as Adrian Mellon

Taylor Frey as Don Hagarty

Stephen Bogaert as Alvin Marsh

Stephen King as Shopkeeper

Peter Bogdanovich as Peter

Will Beinbrink as Tom

Jess Weixler as Audra Phillips

Martha Girvin as Patty

Ryan Kiera Armstrong as Victoria Fuller

Jake Weary as Webby

Katie Lunman as Chris Unwin

Kelly Van der Burg as Victoria's Mom

Jason Fuchs as Richie's Manager

Joe Bostick as Mr. Keene

Megan Charpentier as Young Gretta

Juno Rinaldi as Gretta

Neil Crone as Chief Borton

Ry Prior as Connor

Owen Teague as Dead Hockstetter

Jake Sim as Belch Huggins

Logan Thompson as Victor Criss

Connor Smith as Carny

Amanda Zhou as Waitress

Rob Ramsay as Meaner Nurse

John Connon as John Koontz (Juniper Hill Security)

Doug MacLeod as Head Honcho

Brandon Crane as Big Guy

Erik Junnola as Scuzzah

Josh Madryga as Scuzzah

Peter George Commanda as Shokopiwah Shaman

Kiley May as Shokopiwah Woman

Lisa Cromarty as Shokopiwah Woman

Kevin Allan Hess as Shokopiwah Man

Stephen R. Hart as Shokopiwah Man

Rocky L. Burnham Jr. as Shokopiwah Man

Billy Merasty as Shokopiwah Man

Sladen Peltier as Shokopiwah Young Boy

Ari Cohen as Stanley's Dad

Alex Bird as Theatre P.A.

Brody Bover as Shouting Kid

Edie Inksetter as Shouting Kid's Mom

Martin Julien as Janitor

Sonia Maria Chirila as Fishtank Girl

Colin Mcleod as Bully

Declan Prior as Bully

Marko Vujicic as Bully

Eric Woolfe as Nurse

Kate Corbett as Dean's Mom

Shawn Storer as Dean's Dad

Janet Porter as Richie's Mom

Scott Edgecombe as Customer

Anthony Ulc as The Butcher

J. Bogdan as Swearing Patient

Louise Stratten as Audra's Assistant

Laura Thorne as Production Assistant

Thomas Duhig as Assistant Director

Carla Guerrier as Police Officer

Liam MacDonald as Dean's Friend

Chris D'Silva as Dean's Friend

Tristan Levi Cox as 4-Year-Old Young Mike

Torian Matthew Cox as 4-Year-Old Young Mike

Lola Del Re Hudson as Betty Ripsom's Legs

Thiago Dos Santos as Twitchy Man

Vanzie Meyer as Audience Member (uncredited)

Andy Muschietti as Pharmacy Customer (uncredited)