Horton Hears a Who! (also known as Dr. Seuss' Horton Hears a Who! or simply Horton) is a 2008 American animated adventure musical comedy film based on the 1954 book of the same name by Dr. Seuss, produced by Blue Sky Studios and distributed by 20th Century Fox. The film was directed by Jimmy Hayward and Steve Martino, from a screenplay written by the writing team of Cinco Paul and Ken Daurio. It stars the voices of Jim Carrey and Steve Carell as Horton the Elephant and Mayor Ned McDodd, respectively, alongside Carol Burnett, Will Arnett, Seth Rogen, Dan Fogler, Isla Fisher, Jonah Hill, and Amy Poehler. Recurring Blue Sky collaborator John Powell composed the film's musical score. It is the fourth screen adaptation of the book following the 1970 Chuck Jones television special, the 1987 Soviet animated short, and the 1992 Russian animated short.

Plot

In the Jungle of Nool, Horton the Elephant, the jungle's eccentric nature teacher, hears a tiny yelp coming from a floating dust speck and gives chase to it before placing it on top of a flower. Horton finds out the speck harbors the city of Whoville and its inhabitants, the Whos, led by Mayor Ned McDodd, whose family includes his wife, Sally; 96 daughters whose names all begin with the letter H; and one teenage son named JoJo. Despite being the oldest child and next in line for the mayoral position, JoJo does not want to be the next mayor, and he does not speak due to his fear of disappointing his father.