[[caption-width-right:250: Make the change.]]

->''"We can't tell you who we are. Or where we live. It's too risky, and we've got to be careful. Really careful. So we don't trust anyone. Because if they find us... well, we just won't let them find us.''

->''The thing you've got to know is that ''everyone'' is in really big trouble. Yeah. Even you."''
-->-- '''Blurb''' found on the back of a majority of the ''Animorphs'' books prior to book ''#51: The Absolute''.

One night, five teenagers discover that [[TheVirus parasitic aliens]], called Yeerks, are secretly infiltrating Earth by [[PuppeteerParasite taking over people's bodies]]. They encounter an alien who is on their side, an [[OurCentaursAreDifferent Andalite]] named Elfangor, who, before dying from injuries sustained when his spaceship crashed, gives them the power to [[VoluntaryShapeshifting morph into any animal they have touched]]. Joined by Elfangor's younger brother and unable to trust almost anyone else, they begin a violent and secretive [[LaResistance guerrilla war]] against the invading Yeerks to save the Earth.

During the course of the series, the six teenagers grow from fun-loving kids into an elite team of paramilitary troops, attacking the Yeerk invasion force wherever it is discovered. Along the way, they find allies that they never expected, enemies that prove more dangerous (and, in some cases, [[StarfishAliens bizarre]]) than the Yeerks themselves could ever be, travel to alien worlds, and confront their own inner conflicts. Month after month of pressure begins to take its toll, and the kids are irrevocably changed from the innocent suburban youths they once were.

It supplanted ''Literature/{{Goosebumps}}'' as the most popular children's book series of the mid-1990s till the Millennium despite its incredibly dark setting and content, or perhaps because of it. Like Creator/JKRowling, the author credits herself as Creator/KAApplegate to [[MoustacheDePlume obscure her gender]]; the books were co-authored by her husband Creator/MichaelGrant, [[Literature/{{Gone}} an accomplished author]] [[Literature/{{BZRK}} in his own right]], and most later books were ghostwritten so that Applegate could write ''Literature/{{Everworld}}''. Applegate did still write the outlines, however, and she came back for the two-book finale.

The series heavily deconstructed the RecruitTeenagersWithAttitude / WakeUpGoToSchoolSaveTheWorld concept, turning what could have been a Saturday morning cartoon into pure horror. WarIsHell is in full effect, with the six protagonists having nightmares about the horrors they have to endure, they're silently tormented by the morally questionable things they do, the battle against the Yeerks errodes their personal lives and relationships, and over the course of the series they shed their innocence to become battle-hardened soldiers before they're even legally adults. Additionally, it is emphasized repeatedly that their efforts are ''not'' enough: the Yeerks have infinite resources, an infinite army, anyone they know could betray them, and they try to balance the war with their normal lives so none of the enemy work out who they are, to target their families. All they can do is sabotage the Yeerks until the Andalites ''hopefully'' send their fleet one day to save the Earth, but in the meantime they are only delaying the inevitable.

Responding to fan reaction to the ending, Applegate wrote [[http://web.archive.org/web/20010807200502/www.morphz.com/posts/1061001.htm this letter]].

The franchise included fifty-four regular installments, four extra-length specials (the ''Megamorphs''), two ''ChooseYourOwnAdventure''-style books (which are generally considered to be of low quality), four backstory specials (The ''Andalite'', ''Hork-Bajir'' and ''Ellimist Chronicles'' and ''Visser''), a [[Series/{{Animorphs}} short-lived TV series adaptation]] by {{Creator/Nickelodeon}}, a series of tie-in ''Franchise/{{Transformers}}'' toys, and [[LicensedGame Game Boy and PC games]]. A re-release of the series began in [[http://www.hiracdelest.com/blog/?p=543 summer 2011 with new 3D/animated covers,]] rewriting some of the more dated elements and also clearing up some {{Continuity Drift}}. Unfortunately, the lack of widespread marketing and poor sales of the rereleases [[http://www.hiracdelest.com/blog/?p=4491 led to its cancellation]].

On September 9th, 2015, rumors of Creator/{{Universal}}'s interest in an Animorphs film began to spread. The rumors purport that Deborah Forte (of Silvertongue Films and Scholastic's long-time media adaptation producer) and Universal Pictures are interested in making it happen and are currently searching for a writer/director.

[[http://tvtropes.org/pmwiki/crowner.php/BestEpisode/Animorphs Now]] there's a best installment crowner! Please note that while it's listed under "Best Episode", this does NOT cover the TV series.

Has a [[Characters/{{Animorphs}} character sheet]].

For the TV series, see ''Series/{{Animorphs}}''.

'''WARNING: unmarked spoilers ahead.'''
!!This series provides examples of:

* Animorphs/TropesAToH
* Animorphs/TropesIToP
* Animorphs/TropesQToZ

-->''[[TrademarkFavoriteFood "Cinnamon BUN-ZUH!"]]''