Cast[]
- The Cat in the Hat as Dexter
- Norval the Fish as Tail Dexter
- Cindy Lou Who as Dee Dee
- Sarah Hall-Small as Dexter's Mom
- Mack the Turtle as Dexter's Dad
- Mr. Brown as Dexter's Grandpa
- The Grinch as Mandark
- The White-Tufted Floozle Bird as Lee Lee
- Pam-I-Am as Mee Mee
- Sam-I-Am as Dexter's Monkey
- Little Cat Fleep as Valhallen
- The Once-Ler as Mandark's Duck
- Joey as Mayor Glory
- Horton the Elephant as Krunk
- Jane Kangaroo as Lalava
- The Lorax as Douglas
- Mr. Knox and Fox in Socks as Mitch and Clem
- Young Cat in the Hat as Dextor
- Sylvester McMonkey McBean as Action Hank
- Daisy-Head Mayzie as Pony Puff Princess
- Thidwick the Big-Hearted Moose as Koosalagoopagoop
- Audrey as Agent Honeydew
- North-Going Zax as School Bully #1
- South-Going Zax as School Bully #2