Jesse McCartney is an American actor and singer-songwriter. He achieved fame in the late 1990s on the daytime drama All My Children as JR Chandler. He later joined boy band Dream Street, and eventually branched out into a solo musical career. Additionally, McCartney has appeared on shows such as Law & Order: SVU, Summerland, and Greek. McCartney also is known for lending his voice as Theodore in Alvin and the Chipmunks (2007), Alvin and the Chipmunks: The Squeakquel (2009), Alvin and the Chipmunks: Chipwrecked, Alvin and the Chipmunks: The Road Chip (2015) as well as voicing JoJo McDodd in Horton Hears a Who! (2008), Robin/Nightwing in Young Justice, and Roxas and Ventus in the video game series Kingdom Hearts developed by Square Enix.

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.