- Directors: Jimmy Hayward, Steve Martino
- Producers: Bob Gordon, Chris Wedge
- Writers: Dr Seuss, Ken Daurio, Cinco Paul
- Genres: Animation, Adventure, Comedy, Family
- Actors: Jim Carrey, Steve Carell, Carol Burnett, Dan Fogler, Will Arnett, Amy Poehler, Jaime Pressly, Seth Rogen, Jesse McCartney, Isla Fisher, Jonah Hill, Selena Gomez
In the jungle of Nool on the fifteenth of May, a caring, imaginative elephant named Horton (Jim Carrey), the jungle’s nature teacher, takes a dip in the pool. A dust speck floats past him in the air, and he hears a tiny yelp coming from it. Believing that an entire family of microscopic creatures are living on that speck, he places it on top of a clover that he holds in his trunk.
In fact, he finds out the speck harbors the city of Whoville and all its inhabitants, led by Mayor Ned McDodd (Steve Carell). He has a loving wife, Sally (Amy Poehler), 96 daughters (all voiced by Selena Gomez and Samantha Droke), and one son named Jojo (Jesse McCartney), who, by Who custom, is next in line for the mayoral position. Jojo does not want to become mayor, which leads him to become sullen and refuse to talk, despite Ned’s giving him extra attention.
The Mayor finds out from Dr. Larue that Whoville will be destroyed if Horton doesn’t find a “safer more stable home.” So Horton resolves to place the speck atop Mt. Nool, the safest place in the jungle. This outlook earns Horton nothing but ridicule from the inhabitants of Nool, especially from the strict official of the jungle, the Sour Kangaroo (Carol Burnett), who tries to get Horton to give up the speck, so as not to put supposedly ridiculous ideas into the heads of the children. Ever faithful to his motto, “A person’s a person, no matter how small,” Horton refuses. Also taking force toward Horton are the Wickersham brothers (consisting of Yummo, voiced by Dan Fogler, along with Frank Welker and Dan Castellaneta), a group of bullying monkeys who love making misery.
Hearing the Whos’ cries, Rudy (Josh Flitter), the Kangaroo’s son (who has been in his mother’s pouch the whole movie despite being at the age where kangaroos usually begin living by themselves), grabs the clover and returns it to Horton, refusing his mother’s orders to return to her pouch. The animals finally realize the atrocity they almost committed. The Kangaroo is sad and sorry for her bad behavior, but Horton forgives her, and offers his friendship, which the Kangaroo accepts. At the end of the film, everyone helps Horton carry the speck up to the top of Mt. Nool. After a big number of the cast singing REO Speedwagon’s “Can’t Fight This Feeling”, the camera zooms out, revealing that along with numerous other worlds in our universe, the jungle of Nool is just one speck among numerous others like our planet.