Animorphs: The Invasion 

The Invasion is the first book in the Animorphs series by K.A. Applegate, where five teenagers—Jake, Rachel, Tobias, Cassie, and Marco—gain the power to morph into any animal they touch after encountering a dying alien, an Andalite, who warns them of a secret alien invasion by parasitic Yeerks. They become the Animorphs, fighting a secret war to save humanity by using their morphing abilities to outsmart the invaders, who can possess human hosts. The book introduces the core conflict, the morphing power, and the main characters, setting up the series' science fiction and action-adventure themes. 

The iconic cover for Animorphs #1: The Invasion (1996) was created by artist David B. Mattingly. He used a digital morphing program called Elastic Reality and combined it with traditional painting to create the transforming, photorealistic effect. Photographer Addie Passen took the photos of the models used on the covers.