Darwin is one of the main characters on The Wild Thornberrys. He is a chimpanzee who travels with the family and is a loyal companion to Eliza. He usually wears a tank top with horizontal blue and white stripes (used to be Debbie's lucky tank top) and blue shorts. He speaks with a distinct upper-class British accent. He tries to be the voice of reason to Eliza, however she rarely takes his advice. Cautious by nature, he is almost always hesitant to follow her plans; in response, she accuses him of cowardice, once calling him a "crybaby in a tank-top" for his hesitancy. He was found by Eliza, and was the first animal she ever talked to. In the Wild Thornberrys Movie: The Origin of Donnie, Darwin was seen in a flashback, stealing the sleeveless tank top that was once owned by Debbie. His name is most likely a reference to Charles Darwin, though within the series Eliza gives him the name Darwin after Lenny Darwin, her cousin who looks like a monkey (is never shown in the series).