Oyuncular

• Sherry Lynn — Additional Voices (voice)
• Jim Carrey — Horton (voice)
• Steve Carell — The Mayor of Whoville (voice)
• Carol Burnett — Kangaroo (voice)
• Seth Rogen — Morton (voice)
• Dan Fogler — Councilman / Yummo Wickersham (voice)
• Amy Poehler — Sally O'Malley (voice)
• Niecy Nash — Miss Yelp (voice)
• Jesse McCartney — JoJo (voice)
• Selena Gomez — Helga (voice)
• Bob Bergen — Additional Voices (voice)
• Will Arnett — Vlad (voice)
• Isla Fisher — Dr. Mary Lou Larue (voice)
• Jonah Hill — Tommy (voice)
• Jaime Pressly — Mrs. Quilligan (voice)
• Charles Osgood — Narrator (voice)
• Josh Flitter — Rudy (voice)
• Joey King — Katie (voice)
• Jack Angel — Old Time Who / Additional Voices
• Jan Rabson — Town Cryer / Additional Voices
• John Cygan — Who / Additional Voices
• Jess Harnell — Another Who / Additional Voices
• Debi Derryberry — Who Mom / Additional Voices
• Ariel Winter — Additional Voices (voice)
• Madison Davenport — Additional Voices (voice)
• Samantha Droke — Hildy / Holly (voice)
• Bill Farmer — Willie Bear (voice)
• Heather Goldenhersh — Who Girl (voice)
• Jimmy Hayward — Obnoxious Who (voice)
• Laraine Newman — Glummox Mom (voice)
• Colleen O'Shaughnessey — Angela (voice)
• Laura Ortiz — Jessica (voice)
• Joe Pasquale — The Dentist (voice)