Voiced by: Nika FuttermanA human boy who was transferred from Chester Arthur Middle School to Charles Darwin Middle School by an accidental misspelling of his last name from "Lyon" to "Lion".
Voiced by: Rob PaulsenA highly intelligent lowland gorilla who serves as the anti-bully at the school and often gives confusing wisdom to people. He speaks in a soft-spoken and nearly monotonous manner, often stringing together technical words as a matter of his normal speech.
Voiced by: Rob PaulsenAn easy-going, street-talking green tree python. He is an underachiever and excessive daydreamer who's gullibility allows him to believe anything he hears, which makes him a constant source of misinformation.
Voiced by: Phil LaMarrA bull shark and the school's bully.
Voiced by: Dee Bradley BakerMiss Chameleon
Voiced by: Nika Futterman
Voiced by: Tom Kenny and Robert Goulet in Animal School Musical
Voiced by: Dannah Feinglass