Zac Efron Ted Wiggins (voice)
Danny DeVito The Lorax (voice)
Taylor Swift Audrey (voice)
Ken Daurio Executive Producer, Screenplay
Cinco Paul Executive Producer, Songs, Screenplay
Rob Riggle Mr. Aloysius O'Hare (voice)
Nasim Pedrad Once-ler's Mom (voice)
Chris Renaud Director, Forest Animals (voice)
Betty White Grammy Norma (voice)
Jenny Slate Mrs. Wiggins (voice)
Stephen Tobolowsky Uncle Ubb (voice)
Ed Helms Once-ler (voice)
Dennis Leonard Supervising Sound Editor
Chris Meledandri Producer
Michael Beattie 2nd Marketing Guy (voice)
Danny Mann Additional Voices (voice)
Debi Derryberry Additional Voices (voice)
John Powell Original Music Composer, Songs
Fletcher Sheridan Cy (voice)
Laraine Newman Additional Voices (voice)
Bob Bergen Additional Voices (voice)
Dave B. Mitchell 1st Commercial Guy (voice)
Jim Ward Additional Voices (voice)
Jess Harnell Additional Voices (voice)
Claire Dodgson Editor
Bill Farmer Additional Voices (voice)
Mona Marshall Additional Voices (voice)
Dr. Seuss Book
Randy Thom Sound Designer, Sound Re-Recording Mixer, Supervising Sound Editor
Mickie McGowan Additional Voices (voice)
Gary Rizzo Sound Re-Recording Mixer
Jack Angel Additional Voices (voice)
Ken Schretzmann Editor
Jan Rabson Additional Voices (voice)
Audrey Geisel Executive Producer
Joel Swetow 1st Marketing Guy (voice)
Dempsey Pappion 2nd Commercial Guy (voice)
John Cygan Additional Voices (voice)
Sherry Lynn Additional Voices (voice)
Kyle Balda Co-Director
Danny Cooksey Brett / Chet (voice)
Elmarie Wendel Aunt Grizelda (voice)
Fabrice Joubert Animation
Daniel Laurie ADR Supervisor, Dialogue Editor
Carter Goodrich Character Designer
Mitja Rabar Animation
Steven Liu Editor
Yarrow Cheney Production Design
Eric Guillon Character Designer
Claira Nicole Titman Additional Voices (voice)
Catherine Catie Lee Lighting Artist
Massimo Ruberto Music Supervisor
Janet Healey Producer