Horton

Mona Marshall as Additional Voices (voice) Steve Carell as Mayor (voice) Joe Pasquale as The Dentist (voice) Bob Bergen as Additional Voices (voice) Sherry Lynn as Additional Voices (voice) Mickie McGowan as Additional Voices (voice) Grace Rolek as Additional Voices (voice) Ariel Winter as Additional Voices (voice) John Cygan as Who (voice) Jess Harnell as Another Who (voice) Laraine Newman as Glummox Mom (voice) Danny Mann as Additional Voices (voice) Madison Pettis as Additional Voices (voice) Dan Fogler as Councilman / Yummo Wickersham (voice) Charles Osgood as Narrator (voice) Jack Angel as Old Time Who (voice) Fletcher Sheridan as Jojo (singing voice) (uncredited) Jim Carrey as Horton (voice) Isabella Acres as Additional Voices (voice) Niecy Nash-Betts as Miss Yelp (voice) Jesse McCartney as JoJo (voice) Debi Derryberry as Who Mom (voice) Heather Goldenhersh as Who Girl (voice) Joey King as Katie (voice) Colleen O'Shaughnessey as Angela (voice) Carol Burnett as Kangaroo (voice) Seth Rogen as Morton (voice) Amy Poehler as Sally O'Malley (voice) Jan Rabson as Town Cryer (voice) Selena Gómez as Helga (voice) Laura Ortiz as Jessica (voice) Madison Davenport as Additional Voices (voice) Bill Farmer as Willie Bear (voice) Isla Fisher as Dr. Mary Lou Larue (voice) Jaime Pressly as Mrs. Quilligan (voice) Josh Flitter as Rudy (voice) Karen Disher as Who Kid (voice) Will Arnett as Vlad (voice) Jonah Hill as Tommy (voice) Samantha Droke as Hildy / Holly (voice) Marshall Efron as Wickersham Guard 1 (voice) Jimmy Hayward as Obnoxious Who (voice) Teresa Ganzel as Additional Voices (voice)

Ken Daurio Screenplay Chris Renaud Storyboard Artist Cinco Paul Screenplay Cal Brunker Storyboard Artist Crystal Chesney Additional Storyboarding Frank Marino Additional Storyboarding John Powell Original Music Composer Steve Martino Director Chris Meledandri Executive Producer Jimmy Hayward Director Chris Wedge Executive Producer Paul Downs Animation Karen Disher Storyboard Artist Audrey Geisel Executive Producer J.G. Quintel Additional Storyboarding Dennis Leonard Supervising Sound Editor Rich Moore Additional Storyboarding Mac Smith Sound Effects Editor Moroni Taylor Storyboard Artist Thomas Cardone Art Direction Randy Thom Sound Designer, Supervising Sound Editor Dr. Seuss Book