On the 14th of September in 2006 ... Jim Carrey and Steve Carell joined the HORTON film mix.

The two comedy superstars will headline the cast of voices for Dr. Seuss' Horton Hears a Who, a new CG animated feature film from 20th Century Fox Animation, the makers of the Ice Age films. Carrey, who previously inhabited the world of Dr. Seuss as the title character in the smash hit The Grinch" will voice the role of the immortal Horton, the elephant who knows that a person's a person, no matter how small. Carell will voice the Mayor of Who-ville, a distinguished figure of a very small size, too small to be seen by the elephant's eyes.

The casting was announced by Chris Meledandri, president of Twentieth Century Fox Animation.

Twentieth Century Fox will release Horton Hears a Who March 14, 2008.

The film marks the first time Carrey has lent his voice and talent to bring a CGI animated character to life. Carrey will next be seen this February in the psychological thriller The Number 23, directed by Joel Schumacher, and is set to star with Cameron Diaz in "A Little Game," to be directed by Gabriele Muccino.

Carell, who won the Golden Globe and was Emmy-nominated for his role in the Emmy-winning sitcom The Office, starred in the blockbuster film comedy The 40 Year Old Virgin and is currently starring in Little Miss Sunshine.

The film is based on the beloved book, first published in 1954, by Ted Geisel, who wrote under the pen name Dr. Seuss. Seuss books are among the defining works of family literature, have sold over 200 million copies, and have been translated into fifteen languages. The "Horton" series ("Horton Hears a Who," "Horton Hatches the Egg") are consistently among the top-selling of all Seuss titles -- generation after generation.

Horton Hears a Who is about an imaginative elephant who hears a cry for help coming from a tiny speck of dust floating through the air. Suspecting there may be life on that speck and despite a surrounding community which thinks he has lost his mind, Horton is determined to help.

Horton Hears a Who is from Twentieth Century Fox Animation's Blue Sky Studios, whose recent Ice Age: The Meltdown grossed $650 million in worldwide theatrical box office. Jimmy Hayward and Steve Martino will direct. The script adaptation is written by Cinco Paul and Ken Daurio. The executive producers are Audrey Geisel, Chris Wedge and Chris Meledandri, and the producer is Twentieth Century Fox Animation production executive Bob Gordon. Twentieth Century Fox Animation VP John Cohen is overseeing the project.

Chris Meledandri, who guided the ICE AGE films from their inception, said of Horton Hears a Who, "At the heart of the movies that we make are the characters, and in Horton, Geisel has created a character with an unwavering moral center, a charming innocence, and a selfless willingness to protect others, even at his own expense. Of the 44 books he wrote, Horton Hears a Who is one of his strongest narratives, with enormous stakes -- the entire fate of a world hangs in the balance. Geisel had one of the greatest imaginations of the twentieth century, and Jim Carrey's extraordinary talents are a wonderful match to Geisel's vision. Steve Carell will not only be bringing his great comedic abilities to the role of the Mayor but also his uncanny gift of finding the humanity in every character he plays.

"The film's CG imagery," Meledandri added, "and the extraordinary artists at Blue Sky Studios will give us the opportunity to truly transport audiences into a Seuss world for the very first time."

Dr. Seuss' Horton Hears a Who was released March 14th, 2008 and stars Jim Carrey, Steve Carell, Carol Burnett, Will Arnett, Seth Rogen, Dan Fogler, Isla Fisher, Jonah Hill. The film is directed by Jimmy Hayward, Steve Martino.