Coming Soon spreads the news that Carol Burnett, Seth Rogen, Will Arnett, Isla Fisher, Dan Fogler, Amy Poehler, Dane Cook, Jaime Pressly and Jonah Hill are all lending their voices for Fox/Blue Sky’s Horton Hears a Who. The stars join a cast that already includes Jim Carrey in the title role of Horton, as well as Steve Carell as the Mayor of Who-ville.