- Kathy Najimy
- Kathy Lane
- Matt Frewer
- The Cat in the Hat
- Christopher Lloyd
- Mr. Hunch
- Graham Jarvis
- The Farmer
- Brady Bluhm
- Marco (segment "McElligot's Pool")
- Andrea Martin
- The Ad Woman
- David Paymer
- The Ad Man
- J.D. Daniels
- Marco (segment "Mulberry Street")
- Patrick Stewart
- Sgt. Mulvaney
- Billy Crystal
- The Voice of America
- Andraé Crouch
- Yertle
- Bright Eyes
- Mack
- Maxi Anderson
- Turtle Choir Member
- Troy Burgess
- Turtle Choir Member
- Reggie Burrell
- Turtle Choir Member
- Rick Charles
- Turtle Choir Member
- Sandra Crouch
- Turtle Choir Member
- Kristle Murden
- Turtle Choir Member
- Voncielle Faggett
- Turtle Choir Member
- David Gibson
- Turtle Choir Member / Green Eggs and Ham Player
- Tammie Gibson
- Turtle Choir Member
- Kathy Hazzard
- Turtle Choir Member
- Linda McCrary
- Turtle Choir Member
- Gene Montoya
- Turtle Choir Member / Green Eggs and Ham Player
- Kim O'Kelley
- Turtle Choir Member
- Alfie Silas
- Turtle Choir Member
- Kevin Alexander Stea
- Turtle Choir Member
- Bambi Swayze
- Turtle Choir Member
- Jonathan Webb
- Turtle Choir Member
- Robin Williams
- The Father
- Zelda Williams
- Daughter
- Eleanor Columbus
- Daughter
- Howie Mandel
- Sam-I-Am
- Raymond Del Barrio
- Green Eggs and Ham Player
- TJ Espinoza
- Green Eggs and Ham Player
- Susan Lonergan
- Green Eggs and Ham Player
- Eileen Brennan
- The Who-Villian
- Terry Lindholm
- The Onceler
- Kay E. Kuter
- Dr. Seuss
- Frank Welker
- Mayzie / Horton / Egg / Mouse / Short Hunter / Fat Hunter / Tall Hunter / Elephant Bird / Audience Members / Hitler Lives Narrator / Van Itch / Chief Yookeroo (voice)
- Malachi Pearson
- Additional Voice Over
- Winston Churchill
- Self - at Potsdam
- Charles Durning
- Grandfather Yook
- June Foray
- Cindy Lou Who
- Rudolf Hess
- Self - with Hitler in Nuremberg
- Adolf Hitler
- Self
- Bob Holt
- Lorax / The Onceler / Sylvester McMonkey McBean / Sneetches (voice) (archive footage) (uncredited)
- Boris Karloff
- The Grinch
- William D. Leahy
- Self - at Potsdam
- Vyacheslav Molotov
- Self - at Potsdam
- Dr. Seuss
- Self
- Joseph Stalin
- Self - at Potsdam
- Julius Streicher
- Self - with Hitler in Nuremberg
- Paul Winchell
- Sneetches
