Cassie hi res
Biographical information
Aliases Tree hugger, Mother Earth
Species Human
Caterpillar (briefly)
Gender Female
Eye color Brown
Hair color Black
Born c.1984-1985
Family Michelle (mother)
Walter (father)
Occupation Student
Assistant at Wildlife Rehabilitation Clinic
Diplomat for the Free Hork-Bajir
Yeerk Peace Movement
Affiliation Animorphs
Behind the scenes
First appearance The Invasion
Last appearance The Beginning
Portrayer Biko (book covers)
Nadia-Leigh Nascimento (TV series)
Masasa Moyo (voice, PC game)
Marilyn Alldredge (voice, PlayStation game)
"I’m not trying to be some kind of martyr, or say that I’m always a screwup. I’m not. In my world, making hard choices is part of the deal. Sometimes I’m right, sometimes I’m wrong. Sometimes I just can’t tell, even when the mission is over and we’ve all come out alive, at least."

Cassie is the heart of the Animorphs and easily the best morpher, an estreen.


Cassie is the most compassionate member of the Animorphs, Rachel's best friend, and Jake's girlfriend. She is very kind and empathetic, often acting as the mediator of the group. Her perceptive and caring nature allows her to sense people's inner feelings and insecurities, leading her to act as team therapist at times. Cassie is often a source of the animals morphed by the group.

Cassie's family owns a farm that has been in the family since the Civil War, and has been remodeled into the Wildlife Rehabilitation Clinic; a sort of animal hospital for livestock and wild animals. The Animorphs generally use the clinic as their team "base" and form most of their plans there. Cassie's mother also works at The Gardens, a combination of a zoo and an amusement park. Most of the groups' morphs are acquired from The Gardens or the clinic.

Cassie has the reputation of being a "tree-hugger," due to her love for animals and lack of style. Her nature-loving personality isn't at all shallow though; Cassie has numerous moral struggles and questions about evolution, sentience in animals, the so-called "circle of life," and the morality of the Animorphs' fighting in the war at all. Though Cassie is willing fight when necessary, she desperately seeks a better way to win the war. At one point after a particularly gruesome battle, Cassie decides to quit the team. She pledges to Jake that as long as she isn't fighting, she won't use her morphing ability. Later that day, she meets Aftran 942, who is the Yeerk in the body of Karen, a young girl who does not want to be infested. After Cassie and Aftran discuss the ethics of Yeerks taking hosts, Cassie and Aftran make a deal that if Cassie will agree to become a nothlit in a caterpillar's body (which is a slug just like a Yeerk), then Aftran will agree to leave Karen's body and never infest anyone again. Cassie stays in caterpillar morph for more than two hours, but escapes becoming a nothlit when the caterpillar transforms into a butterfly, an event which resets the morphing clock. A few days later, Karen encounters Cassie in the mall and tells her that Aftran kept her promise.[1] Much later, Cassie saves Aftran, who joined the Yeerk Peace Movement, from Visser Three, who wanted to interrogate and torture her.

Though she is openly against most violence, Cassie's empathetic ability to read people means that she can be ruthless when she has to be. For instance, she came up with the plan to trap David in morph by playing to his ego.[2] True to her dream to find another way to win the war than outright destruction of the other side, it was Cassie who allowed the Yeerks to get the Andalite morphing cube, showing the Yeerks that there was another way to see, hear, eat, and experience the other senses they were denied in their natural yeerk forms than through infestation.[3]

The mention of "Father Banion" at the end of The Unknown (as part of Cassie's parents embarassing her about Jake) implies that the family is Catholic.

Relationships with the other Animorphs

Jake: Jake and Cassie have crushes on each other right from the beginning of the series, and a romance slowly develops between them.  They finally kiss in book #26; in later books they both acknowledge the love they have for each other in their narratives, though they have not stated in outright.  Towards the end of the war, their relationship deteriorates and Jake loses trust in Cassie after she lets Tom take the Escafil Device.

Tobias: While they don't interact as often, they are still good friends. He is the closest in attitude to her, and they generally side together on group votes. Cassie's house is physically close to Tobias' territory. In The Beginning, it's mentioned that while Tobias has stopped talking to Jake and Marco (after Rachel's death), he still does keep in touch with Cassie.

Rachel: Cassie and Rachel are best friends, despite being complete opposites.  Their friendship becomes strained in later books, as Rachel becomes increasingly drawn to her warrior side and becomes impatient with Cassie's strong ethical convictions.

Marco: Although they are generally on good terms, Cassie and Marco are not close and don't spend much time together.  There is some personality conflict between them, as Cassie's morality is diametrically opposed to Marco's ruthlessness. However, at the end Cassie notes that she and Marco are really the only "true survivors" of the war and together they agree to try and break Jake of his depression.

Aximili-Esgarrouth-Isthill: Cassie and Ax don't interact often, although she does comfort Ax after Estrid leaves him. When Ax becomes sick with Yamphut, Cassie shows motherly concern for him before she performs life-saving surgery on him.[4] Ax feels hatred for her after she allows Tom to take the Escafil device, though they appear back on good terms later on.


Book Morphs

Morph Book Acquired
Horse The Invasion
Osprey The Visitor
Wolf The Encounter
Squirrel (Magilla) The Message
Dolphin (Monica)
Ant The Predator
Cockroach The Capture
Great Horned Owl
Humpback Whale (Great One) The Andalite's Gift
White Rat (Courtney) The Secret
Striped Skunk ("Mama")
Wolf Spider The Android
Spider Monkey (Unusable, Sario Rip morph) The Forgotten
Jaguar (Unusable, Sario Rip morph)
Parrot (Unusable, Sario Rip morph) The First Journey
Chameleon (Unusable, Sario Rip morph)
Human (Rachel) The Reaction
Racehorse (Minneapolis Max) The Unknown
Parrot The Escape
Hammerhead Shark
Mole The Underground
Mosquito The Decision
Tyrannosaurus Rex (Unusable, Sario Rip morph) In the Time of Dinosaurs
Caterpillar (May be unusable) - Temporary Nothlit The Departure
Butterfly (May be unusable)
African Elephant The Solution
Anteater The Suspicion
Baby Seal The Extreme
Polar Bear (Nanook)
Giant Squid The Exposed
Chimpanzee The Experiment
Eel The Sickness
Yeerk (Illim)
Hork-Bajir (Jara Hamee) The Prophecy
Cockatiel The Proposal
Orca Whale (Swoosh) The Mutation
Cheetah The Weakness
Pit Viper The Arrival
African Cape Buffalo (Aka] the Widow-Maker) The Hidden
Honeybee The Other
Hork-Bajir-Controller The Unexpected
Beaver The Resistance
Dragonfly The Answer
  • According to the Anibase, which can be downloaded here, Cassie has a total 46 morphs in the series.

Television Show Morphs

Morph Episode Acquired
Horse My Name is Jake, Part 2
Rabbit The Message
Cockroach The Escape
Crocodile The Reaction
Mouse (off-screen) The Leader, Part 2
White-headed Capuchin Changes, Part 1

Cassie has a total of 9 morphs.

Books Narrated By Cassie


  • Out of all the members the Ellimist planned to become an Animorph, Cassie had the most importance.
  • She is more talented at morphing than the others. Ax notes that Cassie could easily become a professional Estreen, one who morphs as a form of art, due to her inherent skills.
  • She has the unconscious ability to unravel any alternate/parallel universe/timeline.[5]
  • All of the models for the Animorphs featured on the front and inside cover had been changed since the series began, mostly because the original kids had grown up and moved away to college (since book 41). Only Cassie's model (Biko) remained close enough to still model for Animorphs. And of course Ax, who is actually just a cardboard cutout.
  • She is the only non-narrating Animorph to be in two inside cover illustrations (Book 21 The Threat and Book 28 The Experiment). This is probably due to the fact above (that her model remained available while others didn't).
  • In The Departure, the naturally-occurred morphing timer-reset exception (That Cassie uses at the end of the book) is the second morphing glitch that is shown in the series. The first one being shown in #12: The Reaction, where it is revealed that an animal cannot be acquired if you are allergic to it. These exceptions never occur, nor are exploited in any way, in the series ever again.
  • In The ProphecyAldrea possessed Cassie's body temporarily to find a Yeerk base on the Hork-Bajir homeworld.
  • With the exception of Marco and his family a while earlier, her family is the first to leave their home when the Animorphs evacuate their families to hide in the Hork-Bajir valley after the Animorphs discover that the Yeerks know they are human.
  • In the Animorphs television series, Cassie's battle morph was a horse, as opposed to her wolf morph in the books.
  • In keeping with her non-violent nature, Cassie is the only Animorph who lacks a unique battle morph; she typically assumes a wolf form when required to fight, which the entire team acquired while investigating Yeerk activity in the mountains.
  • In 1999 three different Animorphs toys of Cassie were made.
    • Her transformer toy turned into a wolf.
    • Taco Bell released a Cassie transforming toy that became an anteater.
    • She was one of three Animorphs who combined all together in the Tri-Rex transformer toy to become a comparatively large Tyrannosaurus Rex.
  • Cassie is the only original Animorph not to accompany the group on the mission to rescue Ax at the end of the series, and possibly the sole surviving original Animorph after the series' end.
  • In the TV series, it's Cassie who's allergic to crocodile DNA, not Rachel. Also, unlike Rachel whom would transform into random animal several times when the allergic symptoms shows up, Cassie only suffer partial transformation on random parts of her body instead.


Book Gallery

TV Gallery

Toy and Game Gallery

Animorphs Jake | Rachel | Tobias | Cassie | Marco | Ax
Auxiliary Animorphs James | Collette | Timmy | Kelly | Craig | Erica | Julio | Liam | Tricia | Jessie | Judy | Ray | Pedro | Elena
New Animorphs Jeanne Gerard | Menderash-Postill-Fastill | Santorelli
Other Animorphs David | You


  1. The Departure
  2. The Solution
  3. The Sacrifice
  4. The Sickness
  5. Back to Before