- Written by Dr. Seuss
- Produced by Ted Geisel and Friz Freleng
- Executive Producer David H. DePatie
- Directed by Bill Perez
- Teleplay and Lyrics: Ted Geisel
- Music: Joe Raposo
- Graphic Design: Ira Turek, Roy Morita
- Background: Allison Julian, Andrew Phillipson, Dennis Venizelos
- Checking: Jan Adams, Armand Shaw, Natalie Shirpser
- Animation: Warren Batchelder, Tom Ray, Oliver Callahan, Morey Roden, John Gibbs, Bob Richardson, Lee Halpern, Virgil Ross, Bob Kirk, Ken Walker, Bob Matz, Don Williams, Norm McCabe
- Assistant Animators: Dorris Bergstram, Grinny Parmelo, Holly Forsyth, Raul Salaiz, Burt Nedall
- Film Editors: Robert T. Gillis, Jim Blodgett, Richard Gannon
- Music Editor: Joe Siracusa
- Camera Effects: John Burton, Jr.
- Special Music: Joe Siracusa
- Voice Talents of: Mason Adams, Bob Holt, Frank Welker, Joe Eich
- In Charge of Production: Lee Gunther
- Production Manager: Kathy Condon
- An Marvel Studios Production
Opening on a morning so beautiful that even the Grinch wakes up in a good mood. But his cheerfulness is soon revoked when his reflection in the mirror (possibly an envisionment of his father) talks back to him & reminds him that he's a Grinch & therefore shouldn't be cheerful, by repeating 'the Grinch's Oath with him:
“ A Grinch's unhelpful, unfriendly, unkind, with ungracious thoughts, in an unhealthy mind. A Grinch's uncheerful, uncouth, & unclean. Now say this together: I'M FRIGHTFULLY MEAN! My eyes are both shifty, my fingers are thrifty. My mouth won't smile, not half of an inch! I'm a Grinch! I'm a Grinch. I'M A GRINCH! ” GRINCH AND CAT IN THE HAT'S CARS Out to prove himself to his reflection, the Grinch goes out to cause misfortune. Meanwhile, the Cat in the Hat goes on a picnic & soon crosses paths with the Grinch when the Grinch crashes into his car. The Grinch demands that the Cat "get this crate out of my way", but when the Cat willingly & cheerfully agrees to his demands, the Grinch pursues him in a car chase for mistakenly calling him 'Mr Green-Face'. Realizing he's upset this person, the Cat returns to his house, but the Grinch tracks him there & messes with his voice using a device he has invented the Acoustical Anti Audio Bleeper ("AcousticaAntAudiBleepe"), otherwise known as the Vaccuum Sound Sweeper ("VaccuuSounSweepe"), a machine that sucks out of the air every noise; every sound, & garbles sound waves of noises & sounds of anything that gets sucked in it for 50 miles around. He's undeniably proud of his invention as he sabotages all other nearby sounds, proclaiming himself the 'The Puzzler and Master of Everyone's Ears'. Then the Grinch goes back to his house & builds a "Darkhouse" with which to mess with the Cat's sight, proclaiming, "That Cat's gonna suffer like never before! Ha-ha-ha-ha-ha-ha-ha-ha...!"
The Cat becomes upset with the Grinch's hijinks & has a psychiatry session with him in a thought bubble. Predictably he gets nowhere with the virtual Grinch, so he then decides to go over and have a talk with him, but in the process, the Grinch makes it so dark he can't see where he's going, & he crashes his car. The Cat attempts to hide from the Grinch in a nearby restaurant, but the Grinch's machine continues to mess with reality, & his hijinks cause michief all over the restaurant. The Cat's now furious with the Grinch & ponders to himself how he can change the Grinch, eventually racing through a door & sending himself hurtling into the Grinch's Dimension. There, as he ponders, he has to endure visions of a floating Grinch head of laser lights, a spinning spiral, & getting split into 4 different-colored outlines - blue, green, red, & yellow, which join together to become a white outline, & he turns back into himself. He soon figures it out & rallies everybody in the restaurant to follow him to the Grinch's house. There, he sings a song about the love the Grinch received from his mother while using his umbrella as a conductor's baton. It's unknown what became of him after this.
The Grinch, having a soft spot for his mom, bursts into tears when he hears this, & is afterward told by the spirit of his mom that "everything's going to be all right." Touched, the Grinch disassembles his machines & goes through his change of heart again the next morning. But when his reflection tries to revert him back to a grouch, his dog Max shuts the mirror up with the Vaccuum Sound Sweeper.
- Bob Holt as The Grinch / The Grinch's Mother
- Mason Adams as The Cat in the Hat / Narrator
- Frank Welker as Max / Waiter / Additional voices
- Joe Eich as Chef
- Notice in the selection the Grinch is singing "The Master of Everyone's Ears", the Cat in the Hat's house is alot similar to the Apartment 12-J in whoville as seen in Horton Hears a Who! (Book) where you will see Jojo with a Yo-yo.
- In the Grinch's lair on the 39th floor in his shop, you will see a Throm-dim-bu-lator that has been taken apart as well like Herbie Hart's Throm-dim-bu-later from the book Did I Ever Tell You How Lucky You Are?