''The Cat in the Hat'' is a children's storybook written and illustrated by Creator/DrSeuss in 1957, which started off his series of books for beginning readers. The story opens on two children who are stuck inside their house due to rain while their mother is out, when they suddenly get a visit from the eponymous character, a six-foot-tall cat who wears a [[NiceHat tall striped hat]]. The Cat offers to entertain them by performing various tricks, with help from his funny-looking assistants, Thing One and Thing Two, despite the objections from the kids' pet fish. Eventually, after the Cat and the Things end up making a mess of the house, the kids take control of the situation, and the Cat makes up for it by cleaning the place on his way out right before the mother returns.

The Cat became one of Dr. Seuss' most enduring characters, returning the following year in a {{sequel}} titled ''The Cat in the Hat Comes Back'', in which he leaves a "cat ring" in the bathtub and spends the rest of the book spreading the spot around in an attempt to get rid of it. In addition, he hosted three other books by Seuss and also served as the narrator for the otherwise unrelated ''Daisy-Head Mayzie'' (published after Seuss' death).

It got [[WesternAnimation/TheCatInTheHat adapted]] in 1971 by [=DePatie-Freleng=] Studios which expands upon the storyline. It was followed up with ''Creator/DrSeuss On the Loose'' (in which the Cat introduced animated adaptations of ''Literature/TheSneetches'', ''The Zax'', and ''Literature/GreenEggsAndHam'') and ''WesternAnimation/TheGrinchGrinchesTheCatInTheHat'' (in which the Cat matches wits with the title character of ''WesternAnimation/HowTheGrinchStoleChristmas''). The Cat later starred in puppet form in ''Series/TheWubbulousWorldOfDrSeuss''. The original book also got a LivingBooks title.

A [[Ride/TheCatInTheHat ride]] based off of the book opened with the [[Ride/UniversalStudios Universal's Islands of Adventure]] park in 1999.

It was [[Film/TheCatInTheHat adapted to film]] in 2003, but got critically panned, especially by the Geisel estate that no longer gives support for live-action adaptations for Dr. Seuss films. There is apparently an animated reboot [[http://www.deadline.com/2012/03/dr-seuss-the-cat-in-the-hat-get-new-life-at-chris-meledandris-illumination/ in production]] at [[WesternAnimation/DespicableMe Illumination]] [[WesternAnimation/TheLorax Entertainment]], effectively putting the live action film under DisownedAdaptation.

Is currently starring in the EdutainmentShow ''WesternAnimation/TheCatInTheHatKnowsALotAboutThat'' on PBS.
!!The books contain examples of:

* AnAesop: "It's fun to have fun, but you need to know how!" A little silliness and mischief is fine, but it's important to know when to stop.
* BlueAndOrangeMorality: The cat is never malevolent. He is simply trying to have fun and doesn't understand the damage he is doing.
* ConstrainedWriting: It was written using a specific constrained vocabulary consisting only of words you'd expect a six-year-old to know.
* MatryoshkaObject: The Cat has Little Cat A under his hat, who has Little Cat B under its hat and so forth. [[spoiler:Underneath Little Cat Z's hat is the "Voom", which unleashes some kind of divide by zero effect only for when the GodzillaThreshold has been reached (in the case, cleaning up the yard.)]]
* NoNameGiven: The boy who narrates the story is never given one.
** Ditto for the cat himself (as well as that fish).
* OnlySaneMan: The Fish.
* OrderVersusChaos: The Cat is a TricksterArchetype {{Ubermensch}} who calls for tearing down the old social order. His foil is a fish who insists on maintaining respect for traditional authority figures.
* PersonWithTheClothing
* PutOnABus: Despite being a prominent character in the first book, the fish is never even mentioned in the sequel. Partly justified since most of the story takes place outside, and because the kids remembered their last encounter with the Cat and are far less trusting of him as a result, making the fish's role unnecessary.
* RainRainGoAway
* ResetButton: Before he leaves, the Cat always manages to undo all the damage he's caused.
* ScreenToStageAdaptation: A stage version of the book was shown in London sometime in 2011 and was even available on Netflix at one point.
* ScrewySquirrel: The Cat.