 | Jaeden Martell als Bill Denbrough |
 | Bill Skarsgård als It |
 | Jeremy Ray Taylor als Ben Hanscom |
 | Sophia Lillis als Beverly Marsh |
 | Finn Wolfhard als Richie Tozier |
 | Chosen Jacobs als Mike Hanlon |
 | Jack Dylan Grazer als Eddie Kaspbrak |
 | Wyatt Oleff als Stanley Uris |
 | Nicholas Hamilton als Henry Bowers |
 | Jake Sim als Belch Huggins |
 | Logan Thompson als Victor Criss |
 | Owen Teague als Patrick Hockstetter |
 | Jackson Robert Scott als Georgie Denbrough |
 | Stephen Bogaert als Mr. Marsh |
 | Stuart Hughes als Officer Bowers |
 | Geoffrey Pounsett als Zach Denbrough |
 | Pip Dwyer als Sharon Denbrough |
 | Molly Atkinson als Sonia Kasprak |
 | Steven Williams als Leroy Hanlon |
 | Elizabeth Saunders als Mrs. Starret |
 | Megan Charpentier als Gretta |
 | Joe Bostick als Mr. Keene |
 | Ari Cohen als Rabbi Uris |
 | Anthony Ulc als Joe the Butcher |
 | Javier Botet als Hobo |
 | Katie Lunman als Betty Ripsom |
 | Carter Musselman als Headless Boy |
 | Tatum Lee als Judith |
 | Edie Inksetter als Hostess |
 | Martha Gibson als Old Woman |
 | Kasie Rayner als Field Hockey Girl #1 |
 | Isabelle Nélisse als Girl in Bathroom |
 | Jocelyn Mattka als Another Girl |
| Donald Tripe als Old Man in Car |
| Liz Gordon als Old Woman in Car |
| Paige Rosamond als Dead Girl #1 |
 | Neil Crone als Chief Borton |
 | Sonia Gascón als Mrs. Ripsom |
 | Janet Porter als Stanley's Mother |
| Memo Díaz Capt. als 4th of July Clown |
| Chantal Vachon als Girl in Magazine |
 | Roberto Campanella als Organ Player Clown |
| Cyndy Day als Pharmacy Cashier (uncredited) |
| David Katzenberg als El Aparato (uncredited) |
| Bobby Leigh als Jonathan (uncredited) |
| Aimee Lenihan als Student (uncredited) |
| Kylie Lenihan als Student (uncredited) |
 | Kate Moyer als Esther (uncredited) |
 | Sherry Nelson als Woman on Street (uncredited) |
 | Jimmy Star als Man in Car (uncredited) |
 | Kelly Van der Burg als Abigail (uncredited) |
| Stephanie Gorin | Casting |
| Kelly Jones | Stunt Coordinator |
| Vincent Rother | Stunts |
| Stephen King | Novel |
| Roberto Campanella | Choreographer |
| Ciara Jones | Stunts |
| Jeong Jeong-hun | Director of Photography |
| Benjamin Wallfisch | Original Music Composer |
| Marty P. Ewing | Executive Producer |
| Marty P. Ewing | Unit Production Manager |
| Paul Flinchbaugh | Assistant Sound Editor |
| Peter Grundy | Art Direction |
| Claude Paré | Production Design |
| Roy Lee | Producer |
| Toby Emmerich | Executive Producer |
| Walter Hamada | Executive Producer |
| Jason Ballantine | Editor |
| Richard Brener | Executive Producer |
| Dan Lin | Producer |
| Sylvain Arseneault | Sound Recordist |
| Dana Sano | Music Supervisor |
| Cary Joji Fukunaga | Screenplay |
| Tom Woodruff Jr. | Makeup Effects Designer |
| William Waring | Second Unit Director |
| Michael Keller | Sound Re-Recording Mixer |
| Seth Grahame-Smith | Producer |
| Brett Pierce | Music Editor |
| Rich Delia | Casting |
| Jon Silk | Executive Producer |
| Alec Gillis | Makeup Effects Designer |
| Jeremy Gillespie | First Assistant Art Direction |
| Steven Kostanski | Makeup Artist |
| Bárbara Muschietti | Producer |
| Andy Muschietti | Director |
| Scott Patton | Concept Artist |
| David Katzenberg | Producer |
| Michael Kearns | Boom Operator |
| Mace Matiosian | Foley Editor |
| Linda Dowds | Makeup Department Head |
| Dan Bronson | Costume Supervisor |
| Christopher Geggie | Property Master |
| Gary Dauberman | Screenplay |
| Nicholas Brooks | Visual Effects Supervisor |
| Richard Cowan | First Assistant Director |
| Brice Liesveld | Visual Effects Producer |
| Chris Jenkins | Sound Re-Recording Mixer |
| Kris Fenske | Sound Effects Editor |
| Janine Parkinson | Stunts |
| Jamie Hardt | Sound Effects Editor |
| Victor Ray Ennis | Supervising Sound Editor |
| Bernard Weiser | Dialogue Editor |
| Shane B. Scott | Script Supervisor |
| Joseph T. Sabella | Foley Artist |
| Lise Richardson | Music Editor |
| Kendrick Wallace | Visual Effects Producer |
| Paul Hackner | Sound Designer |
| Angelo Colavecchia | Steadicam Operator |
| Angelo Colavecchia | "A" Camera Operator |
| Warren Appleby | Special Effects Coordinator |
| Warren Appleby | Special Effects Supervisor |
| Michael Carella | Second Unit Director of Photography |
| Michael Carella | "B" Camera Operator |
| Jamie Jones | Stunt Coordinator |
| Vanessa Galvez | Digital Intermediate Producer |
| Jeff Derushie | Makeup Artist |
| Joe Everett | Unit Publicist |
| Kenny Meinzinger | Set Dresser |
| Michael Galbraith | Chief Lighting Technician |
| Brooke Lyndon-Stanford | Visual Effects Supervisor |
| Neil Morrill | Prosthetic Makeup Artist |
| Laurel Bresnahan | Studio Teachers |
| Lara Ramirez | Visual Effects Editor |
| Scott Cannizzaro | ADR Mixer |
| Simeon Wilkins | Storyboard Designer |
| Henry Fong | Concept Artist |
| Mark Purcell | Sound Mix Technician |
| Tim Williams | Conductor |
| Neil Davison | Stunts |
| Ryan Reed | Hairstylist |
| Janie Bryant | Costume Design |
| Stephanie Ingram | Hair Department Head |
| Jordana Lieberman | Third Assistant Director |
| Brooke Palmer | Still Photographer |
| Glen Gauthier | Sound Mixer |
| Chase Palmer | Screenplay |
| Court Chu | Concept Artist |
| Rob McCallum | Storyboard Designer |
| Daniel Carrasco | Creature Design |
| Jared Krichevsky | Concept Artist |
| Joshua Min | Concept Artist |
| Coco Kleppinger | Casting Associate |
| Tom Farr | Stunts |
| Steve Switzer | Boom Operator |
| Wayne Anderson | Sculptor |
| Eric Deros | Set Designer |
| Stephen Nakamura | Digital Intermediate Colorist |
| Pearce Roemer | First Assistant Editor |
| John Mackenzie | Construction Coordinator |
| Nicola Weston | Art Department Coordinator |
| Brayden Jones | Stunts |
| Richard Emerson | Key Grip |
| Penny Charter | Second Assistant Director |
| Rosalie Board | Set Decoration |
| Debra Manou | Key Hair Stylist |
| Emily O'Quinn | Key Makeup Artist |
| Robin M. Reelis | Production Manager |
| Kenneth L. Johnson | Sound Effects Editor |
| Darin Read | Post Production Supervisor |
| Benjamin Smith | First Assistant "B" Camera |
| Aj Risi | Stunts |
| David J. Krystal | Orchestrator |
| Randy Morgan | Location Manager |
| Dera Veinot | Makeup Artist |
| Adam Richard Benish | Assistant Director |
| Adam Bocknek | Second Assistant Director |
| Nick Lopez | Third Assistant Director |
| Andrew Pritchard | Third Assistant Director |
| Brenton Brown | Set Dresser |
| Jon Chan | Assistant Art Director |
| David DeMarinis | Leadman |
| Michael Derrah | Storyboard Designer |
| Adam Dougherty | Sculptor |
| Paul Greenberg | Assistant Art Director |
| Andrew Lindell | Carpenter |
| Sandor Mate | Carpenter |
| Ryan McCaffrey | Set Dresser |
| Tania McGowan | First Assistant Art Direction |
| Sorin Popescu | Set Designer |
| Dave Rosa | Painter |
| Brian van de Valk | Construction Foreman |
| Brian van de Valk | Carpenter |
| CJ Woodley | Boom Operator |
| Glenn Carter | Location Scout |
| Ron McKenzie | Location Scout |
| Gail Marks | Production Accountant |
| Brad DeWolde | Animal Wrangler |
| Bauston Camilleri | Stunts |
| Chad Camilleri | Stunts |
| Cam Fergus | Stunts |
| Doug Novis | Rigging Gaffer |
| Phil Whitfield | Assistant Chief Lighting Technician |
| Ronald G. Paulauskas | Rigging Grip |
| Robert Cochrane | Dolly Grip |
| Glen Goodchild | Dolly Grip |
| Sarah Craig McEathron | Makeup Department Head |
| Avery Queffelec | Stunts |
| David Allan | Lighting Technician |
| John Vrakking | Key Rigging Grip |
| Thomas J. O'Connell | ADR Mixer |
| William Conrad | Editorial Services |
| Alex Lawrence | Lighting Technician |
| Dean Stinchcombe | First Assistant "A" Camera |
| Sondra Treilhard | Key Hair Stylist |
| Sean Bourdeau | Best Boy Grip |
| Jeff DaSilva | First Assistant Camera |
| Emerson Doerksen | Scenic Artist |
| Henry Ilola | Carpenter |
| Adam Tupper | Second Assistant "A" Camera |
| Brent Jones | Stunts |
| Bryan Thomas | Stunts |
| Tim Cody | Stunts |
| Ilora Rosenberg | Stunts |
| Hillary Holmes | Music Coordinator |
| James B. Howe | Foley Mixer |
| Canaan Davison | Stunts |
| Katharine Duke | Payroll Accountant |
| Dustin Faith | Stunts |
| Jennifer Murray | Stunts |
| Vic Kaspar | ADR Mixer |
| Rose Huggett | Hairstylist |
| Mason Kopeikin | Foley Editor |
| Jesi Ruppel | Foley Artist |
| Kyle Brown | Concept Artist |
| Alan Hemsworth | Greensman |
| Rowena O'Connor | Assistant Property Master |
| Ryan Prouse | Second Assistant "B" Camera |
| Rich Sutherland | Rigging Grip |
| Jeff Dineen | Key Set Costumer |
| Ferran Banchs | Assistant Editor |
| Krista Colosimo | Production Secretary |
| Joan Hug Valeriote | Studio Teacher |
