 | Mike Myers als The Cat |
 | Dakota Fanning als Sally Walden |
 | Spencer Breslin als Conrad Walden |
 | Kelly Preston als Joan Walden |
 | Alec Baldwin als Larry Quinn |
 | Amy Hill als Mrs. Kwan |
 | Sean Hayes als Mr. Humberfloob / Fish (voice) |
 | Danielle C. Ryan als Thing One |
 | Taylor Rice als Thing One |
 | Brittany Oaks als Thing Two |
| Talia-Lynn Prairie als Thing Two |
 | Dan Castellaneta als Thing One / Thing Two (voice) |
 | Victor Brandt als Narrator (voice) |
 | Daran Norris als Announcer |
 | Frank Welker als Nevins (voice) |
 | Clint Howard als Kate the Caterer |
 | Paige Hurd als Denise |
 | Steven Anthony Lawrence als Dumb Schweitzer |
 | Paris Hilton als Female Club-Goer |
 | Candace Brown als Secretary |
| Stephen Hibbert als Jim McFinnigan |
| Roger W. Morrissey als Mr. Vompatatat |
| Norman Fessler als Mailman (uncredited) |
| Bugsy als Nevins |
| Don Zimmerman | Editor |
| Brian Grazer | Producer |
| David Newman | Original Music Composer |
| Karen Kehela Sherwood | Executive Producer |
| Emmanuel Lubezki | Director of Photography |
| Gregg Taylor | Executive Producer |
| Maureen Peyrot | Executive Producer |
| Bo Welch | Director |
| Eric McLeod | Executive Producer |
| Alex McDowell | Production Design |
| Alec Hammond | Supervising Art Director |
| François Audouy | Assistant Art Director |
| Maya Shimoguchi | Assistant Art Director |
| Sean Haworth | Art Direction |
| Luc Desmarchelier | Concept Artist |
| Anne Kuljian | Set Decoration |
| Amy L. Disarro | Makeup Artist |
| Melanie Hughes | Makeup Department Head |
| Bart Barbuscia | Set Dresser |
| Karen E. Burnett | Set Dresser |
| J. André Chaintreuil | Set Designer |
| Clovis Chamberet | Set Dresser |
| Luke Freeborn | Set Designer |
| Victor James Martinez | Set Designer |
| Sam Page | Set Designer |
| Richard Reynolds | Set Designer |
| Hugo Santiago | Set Designer |
| Easton Michael Smith | Set Designer |
| Louis Terry | Set Dresser |
| Brian Basham | Sound Recordist |
| Lance Brown | Sound Effects Editor |
| Richard Dwan Jr. | Dialogue Editor |
| Richard Dwan Jr. | Sound Editor |
| Erich Gann | Sound |
| David Grimaldi | Sound Effects Editor |
| Randall Guth | Sound Effects Editor |
| Beau Hilkene | Sound Effects Editor |
| Michael Hilkene | Supervising Sound Editor |
| Michael Hilkene | ADR Supervisor |
| Ken J. Johnson | Sound Effects Editor |
| Ai-Ling Lee | Sound Effects Editor |
| Steve Maslow | Supervising Sound Editor |
| Charles Maynes | Sound Effects Editor |
| Bruce Tanis | Sound Effects Editor |
| Bernard Weiser | Sound Effects Editor |
| Andre Bustanoby | Visual Effects Supervisor |
| Lisa Clarity | VFX Artist |
| Anders Ericson | Visual Effects |
| Mark Freund | Visual Effects Supervisor |
| Wensen Ho | VFX Artist |
| Ian Hunter | Visual Effects Supervisor |
| Michael Kowalski | Visual Effects Producer |
| Ryan Lastimosa | VFX Artist |
| Philippe Leprince | VFX Artist |
| Allan Magled | Visual Effects Supervisor |
| Richard Malzahn | Visual Effects Supervisor |
| Rodney Montague | Visual Effects Producer |
| Patrick Phillips | Visual Effects |
| Rebecca Ramsey | Visual Effects Producer |
| David Sanger | Visual Effects Producer |
| Erika Wangberg Burton | Visual Effects Producer |
| Edward T. Hanley | Set Costumer |
| Nancy McArdle | Costume Supervisor |
| Rita Ryack | Costume Design |
| Dr. Seuss | Book |
| Alec Berg | Screenplay |
| David Mandel | Screenplay |
| Jeff Schaffer | Screenplay |
| Tyler Allison | Assistant Camera |
| Aldric La'Auli Porter | Associate Producer |
| Arlene Kehela | Associate Producer |
| Gary Archer | Prosthetics |
| Dan O'Connell | Foley Artist |
| John T. Cucci | Foley Artist |
| James Ashwill | Foley Mixer |
| Nancy Thurston | Stunts |
| Andy Gill | Stunts |
| Jack Gill | Second Unit Director |
| Jack Gill | Stunt Coordinator |
| Kenny Endoso | Stunts |
| Darrin Prescott | Stunts |
| Kacie Borrowman | Stunt Double |
| Dean Zimmerman | First Assistant Editor |
