Animorphs is a science fantasy series of middle grade books written by K. A. Applegate (see authorship below) and published by Scholastic. It is told in first person, with all six main characters taking turns narrating the books through their own perspectives. The core themes of the series are horror, war, imperialism, dehumanization, sanity, morality, innocence, leadership, freedom, family, and growing up.
Published between June 1996 and May 2001, the series consists of 54 books and includes ten companion books, eight of which fit into the series' continuity (the Animorphs Chronicles and Megamorphs books) and two that are gamebooks not fitting into the continuity (the Alternamorphs books).
The books were adapted into a television series of the same name on Nickelodeon, YTV and Global, which ran from 1998 to 1999. The series has also been adapted to audiobook form as well as a series of graphic novels starting in 2020. A second television adaptation was announced in 2026.
Plot summary The story revolves around five teenage humans: Jake, Marco, Cassie, Rachel, Tobias, and one alien, Aximili-Esgarrouth-Isthill (nicknamed Ax), who obtain the ability to transform into any animal they touch. Naming themselves "Animorphs" (a portmanteau of "animal morphers"),Animorphs: "The Invasion" they use their ability to battle a secret infiltration of Earth by a parasitic race of aliens resembling large slugs called Yeerk. Yeerks can take any living creature as a host by entering and merging with their brain through the ear canal. The Animorphs fight as a guerrilla force against the Yeerks, led by Visser Three, who uses an Andalite (a centaur-like race of aliens, which Ax belongs to) as a host.
Throughout the series, the Animorphs carefully protect their identities; the Yeerks assume that the Animorphs are a strike force of Andalites, the aliens who created the transformation technology, sent to prevent the Yeerks from conquering Earth. The Animorphs maintain this façade to protect their families from Yeerk reprisals.
Though the Animorphs can assume the form of any animal they touch to acquire the DNA, there are several limitations to the ability. The most vital is that they cannot stay in animal form for more than two hours, or they will be unable to return to human form and the morphs become permanent. The Andalite term for this is "Nothlit". Others include having to demorph back to human in between morphs, only tight clothing being able to be carried over with a morph, DNA allergies that can lose some control of the morphing ability, and having to consistently maintain concentration during a morph to prevent the animal's natural instincts from overwhelming their human intellect. A benefit to morphing is that it allows the team to heal any superficial, non-genetic injury, sustained as a human or in a morph. Also, while in morph, they can telepathically communicate with anyone nearby in what they call 'thought-speak'.
Development Writing The series was originally conceived as a three-part series called The Changelings, in which Jake was named Matt, and his little brother Joseph took the place of Cassie.
In an interview with Publishers Weekly, Katherine Applegate talked about the source of inspiration and realization for the Animorphs series: "I grew up loving animals and lived with the usual suburban menagerie of dogs, cats and gerbils", she said "I really wanted to find a way to get kids into the heads of various species and decided that a science-fiction premise was the way to do this". Applegate tried to accurately depict the various animals, and did research such as visiting "a raptor center where they rehabilitate injured birds". "When Tobias becomes a hawk, I want the reader to see the world as a hawk might see it—to soar on the warm breezes and hurtle toward the ground to make a kill", she said.
To develop the characters for Animorphs, Applegate would go through teenage magazines such as YM and Seventeen (both of which are referenced in the books when describing Rachel), cutting out pictures and piecing them together to get an idea of what sort of children the Animorphs would look like. Applegate stated in an interview online that many of the names for her alien creatures, races, and locations are actually scrambled names of local street signs or companies that she happens to notice. For instance, the word nothlit was derived from the hotel name Hilton. In another interview, Applegate stated that she originally wanted the alien Andalite to have more standard and familiar forms, but was told by Scholastic to be more creative with the designs, which led to her giving them such a distinctive look.
According to the Anibase (an officially-produced, Flash-based piece of software once available on the official Animorphs website with detailed information about each book), Applegate did not make up the titles for the Animorphs books: it was up to the Scholastic editors to create the titles for the books based on the outlines provided by the author, having to select a word that not only fit the book's storyline, but sounded good with the characteristic "The" preface. One of the author's favorite books, The Lord of the Rings, lent several words and images to Animorphs: the Sindarin plural word for Orc, "yrch", became Yeerk; the flaming red Eye of Sauron inspired the Crayak, and Ax's middle name, "Esgarrouth", is based on a town in the books called Esgaroth. The human name of Ax's brother, Elfangor, is Alan Fangor and his last name is in reference to the Fangor region or Fangorn Forest. Also there was a minor reference to Gondor, in the form of a fictional company named "Gondor Industries" in the 14th book.
Authorship Animorphs is published under the name "K.A. Applegate", and was created by husband-and-wife co-authors Katherine Applegate and Michael Grant, though Katherine Applegate is often presented as the single author. Grant described their division of work as running "anything from 50/50 to 90/10". Later graphic novel adaptations were "based on the novels by K.A. Applegate and Michael Grant".
Due to many contributing factors—such as the birth of their child and the difficulties involved in writing Everworld (which was originally intended to be mostly ghostwritten, like Applegate's third Scholastic series Remnants), many of the novels from the #25-#52 range were written by ghostwriters. Typically, Applegate would write a detailed outline for each book, and a ghostwriter, usually one of Applegate's former editors or writing protégés, would spend a month or two writing the actual novel. After this, Applegate, and later series editor, Tonya Alicia Martin, would edit the book to make it fit in with the series' tight continuity. Ghostwriters are credited for their help in the book's dedication page: "The author would like to thank [ghostwriter name] for his/her help in preparing this manuscript".
The following books in the series were ghostwritten:
#25: The Extreme – Jeffrey Zeuhlke #27: The Exposed – Laura Battyanyi-Weiss (Due to an editorial oversight, Battyanyi-Weiss was uncredited for this book.) #28: The Experiment – Amy Garvey #29: The Sickness – Melinda Metz #30: The Reunion – Elise Donner #31: The Conspiracy – Laura Battyanyi-Weiss #33: The Illusion – Ellen Geroux #34: The Prophecy – Melinda Metz #35: The Proposal – Jeffrey Zeuhlke #36: The Mutation – Erica Bobone #37: The Weakness – Elise Smith #38: The Arrival – Kimberly Morris #39: The Hidden – Laura Battyanyi-Weiss #40: The Other – Gina Gascone #41: The Familiar – Ellen Geroux #42: The Journey – Emily Costello #43: The Test – Ellen Geroux #44: The Unexpected – Lisa Harkrader #45: The Revelation – Ellen Geroux #46: The Deception – Elise Donner #47: The Resistance – Ellen Geroux #48: The Return – Kimberly Morris (Due to an editorial oversight, Lisa Harkrader was mistakenly credited for this book.) #49: The Diversion – Lisa Harkrader #50: The Ultimate – Kimberly Morris #51: The Absolute – Lisa Harkrader #52: The Sacrifice – Kimberly Morris Alternamorphs #1 – unknown Alternamorphs #2 – Emily Costello
Cover art
The covers for 55 books in the series were designed by David B. Mattingly. He used the software Elastic Reality for the morphing effect. According to Mattingly, Scholastic was not satisfied with the first two book covers. Then-Creative Director David Tommasino knew Mattingly had experience working digitally and reached out to him. Mattingly had never done a morph before, but ordered a copy of Elastic Reality and completed a sample within two days, which eventually became the cover for book #3: The Encounter.
Each of Mattingly's covers took two weeks to create, from pencil sketch to finished digital render and required painting, since the Elastic Reality program produced smeared or stretched material. Mattingly would do the covers first, then the cutbacks. Since Scholastic wanted the covers to feature photorealistic humans, model reference photos were taken by photographer Addie Passen at her Union Square studio. According to Paige Tiffany, the model for most of Rachel's books, each photoshoot would only take between 30 and 60 minutes. Due to most of the models aging out, only Cassie's model was used continuously throughout the series.
The covers not designed by Mattingly are issues #1: The Invasion (designed by Peter Bollinger), #2: The Visitor (designed by Tim O'Brien), #9: The Secret, #10: The Android and #12: The Reaction (each designed by Damon C. Torres & The I-Way Company). In addition, Romas Kukalis provided cover art for the limited Animorphs Chronicles series. Mattingly used Kukalis' version of the Andalites as reference for his covers.
Characters Animorphs Jake: Jake Berenson is the leader of Animorphs. His battle morph is a tiger, and his flight morph is a peregrine falcon. Despite being a natural leader, he's reluctant to accept the role. The war takes on a deeper meaning for Jake when he finds out that his older brother Tom has been taken over by a Yeerk; this is one of his main motivations, preventing him from cracking under the pressure of making life-or-death decisions throughout the series. He is the only member of the team to have some relationship with all of the other human members prior to the war: Jake and Rachel are cousins, he and Marco have been best friends since early childhood, he is one of the few people who treats Tobias kindly, and he and Cassie have always had an attraction to each other. Jake and Cassie share their first kiss in book 26 and are in a relationship throughout the second half of the series. Rachel: Rachel has the most bloodthirsty nature in the group, earning her the nickname of "Xena, Warrior Princess". Her battle morphs are an African elephant and grizzly bear, and her flight morph is a bald eagle. She is also good in gymnastics and has an interest in fashion. She is Jake's cousin and Cassie's best friend, although her warrior nature often conflicts with Cassie's pacifist mindset. She and Tobias develop an attraction for one another during the series. She also has two younger sisters, Jordan and Sara. In the television series adaptation, her morph is a male lion as opposed to this being the battle morphs of David and James. Tobias: Tobias has low self-esteem and was often bullied in school before becoming an Animorph. An orphan, he lives with his aunt and uncle, who share custody of him. Tobias becomes trapped in a red-tailed hawk form in the first book. During the series, he regains the power to morph, but with his natural form remaining a hawk. Even though Rachel wants him to morph back into a human permanently, he keeps the hawk form in order to retain his morphing powers and continue fighting the Yeerks. Tobias admires Jake because Jake always showed him respect and kindness when no one else did. Also, Tobias develops a close friendship with Ax.