James McAvoy (Bill Denbrough), Jessica Chastain (Beverly Marsh), Isaiah Mustafa (Mike Hanlon), Bill Hader (Richie Tozier), Jay Ryan (Ben Hanscom), James Ransone (Eddie Kaspbrak), Bill Skarsgård (Pennywise) more..., Teach Grant (Henry Bowers), Andy Bean (Stanley Uris), Jaeden Martell (Young Bill Denbrough), Sophia Lillis (Young Beverly Marsh), Jack Dylan Grazer (Young Eddie Kaspbrak), Finn Wolfhard (Young Richie Tozier), Jeremy Ray Taylor (Young Ben Hanscom), Wyatt Oleff (Young Stanley Uris), Chosen Jacobs (Young Mike Hanlon), Nicholas Hamilton (Young Henry Bowers), Javier Botet (Hobo / The Witch), Xavier Dolan (Adrian Mellon), Taylor Frey (Don Hagarty), Molly Atkinson (Myra / Sonia Kaspbrak), Joan Gregson (Mrs. Kersh), Stephen Bogaert (Alvin Marsh), Luke Roessler (Dean), Stephen King (Shopkeeper), Peter Bogdanovich (Peter), Will Beinbrink (Tom), Jess Weixler (Audra Phillips), Martha Girvin (Patty), Ryan Kiera Armstrong (Victoria Fuller), Jackson Robert Scott (Georgie Denbrough), Jake Weary (Webby), Katie Lunman (Chris Unwin), Kelly Van der Burg (Victoria's Mom), Jason Fuchs (Richie's Manager), Joe Bostick (Mr. Keene), Megan Charpentier (Young Gretta), Juno Rinaldi (Gretta), Neil Crone (Chief Borton), Ry Prior (Connor) and others.

Gary Dauberman (Screenplay), Stephen King (Novel), Dan Lin (Producer), Roy Lee (Producer), Paul D. Austerberry (Production Design), Nigel Churcher (Art Direction), Checco Varese (Director of Photography) more..., Jason Ballantine (Editor), Rich Delia (Casting), Shane Vieau (Set Decoration), Luis Sequeira (Costume Design), Shane Zander (Makeup Department Head), Adam Bocknek (Second Unit Director), Marty P. Ewing (Executive Producer), Dave Neustadter (Executive Producer), Bárbara Muschietti (Producer), Benjamin Wallfisch (Original Music Composer), Richard Brener (Executive Producer), Seth Grahame-Smith (Executive Producer), David Katzenberg (Executive Producer), Stephanie Gorin (Local Casting), Catherine Harper (Foley Artist), Marty P. Ewing (Unit Production Manager), Peter S. Elliot (Additional Editor), Sylvain Arseneault (Sound Mixer), Tom Woodruff Jr. (Makeup Designer), Jason Fuchs (Co-Producer), William Waring (Second Unit Director), Michael Keller (Sound Re-Recording Mixer), Alec Gillis (Makeup Designer), Jeremy Gillespie (Graphic Designer), Mélanie Turcotte (Costumer), Randy Singer (Foley Mixer), Linda Dowds (Makeup Artist), Suzanne Aplin (Costume Supervisor), Lisa Shamata (Unit Publicist), Christopher Geggie (Property Master), Gary Dauberman (Executive Producer), Nicholas Brooks (Visual Effects Supervisor), Nancy Nugent (Supervising Sound Editor) and others.