Horton Hears a Who! is a 2008 American animated adventure 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.

Theodor Seuss Geisel was an American children's author and cartoonist. He is known for his work writing and illustrating more than 60 books under the pen name Dr. Seuss. His work includes many of the most popular children's books of all time, selling over 600 million copies and being translated into more than 20 languages by the time of his death.