The Wild Thornberrys

• Eliza (voiced by Lacey Chabert) is the 11-year-old daughter of the Thornberrys. She has red hair in braids, glasses, braces, and freckles. She has four visible teeth connected by two braces. She is able to communicate with animals, especially her chimpanzee sidekick Darwin. She must keep this gift secret or she will lose her powers.[3]
• Nigel (voiced by Tim Curry) is Eliza's father. Sir Nigel Archibald Thornberry KBE is the son of Radcliffe (also voiced by Curry) and Cordelia Thornberry (Lynn Redgrave), an aristocratic British couple. Born in the United Kingdom and having attended Harrow School near London, he travels around the world with his own family making wildlife documentaries. He is eccentric, enthusiastic, and cheerful even in the face of danger, and is also known for his exaggerated facial features.
• Marianne (voiced by Jodi Carlisle) is Eliza's mother and Nigel's wife. She is the daughter of Frank (Ed Asner) and Sophie Hunter (Betty White). She mentions that she attended the University of California, Berkeley.
• Donnie (voiced by Flea) is a feral boy adopted by the Thornberrys, who (as revealed in the 2001 four-part TV movie, "The Wild Thornberrys: The Origin of Donnie") was raised by orangutans in Borneo.[3] Donnie is 4, turning 5 in "The Origin of Donnie".
• Debbie (voiced by Danielle Harris) is Eliza's 16-year-old older sister. She becomes the only family member to know about Eliza's power but is warned that she will be turned into a baboon if she ever tells anyone. Debbie dresses in grunge clothing and has peekaboo hairstyle.
• Darwin (voiced by Tom Kane) is the Thornberrys' pet chimpanzee. 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.

• Neil Biederman (voiced by Michael Jeter & replaced by Jerry Sroka), a poacher & The Thornberrys’ sworn enemy who poaches and kidnaps animals from above it, with his partner Kip O'Donnell (voiced by Keith Szarabajka).
• Tyler Tucker (voiced by Jonathan Taylor Thomas), Eliza and Debbie's cousin. He is Marianne and Nigel's nephew through Marianne's sister Nancy Tucker nee Hunter. He is a year older than Eliza but acts more immaturely than Eliza does. He doesn't really understand the dangers of living in the wild. He's a big know-it-all but generally has a good head on his shoulders, and he really cares about his cousins Debbie, Eliza, and Donnie. His parents are Dennis (voiced by Martin Mull) and Nancy Tucker (voiced by Mary Kay Place).
• Shane G. (voiced by Christopher Masterson) is a pop superstar who travels with the Thornberry Family for five episodes whilst they are filming in Alaska. The Foundation orders Nigel and Marianne to take him with the family to promote Wildlife preservation among young people and Shane's fans. Both Eliza and Debbie gain a crush on the boy, however Debbie loses interest when Shane shows to have more similarities with Eliza than herself.
• Santusa (voiced by Tia Texada), a Llama first seen in Nigel Knows Best. She can carries both of her. Darwin doesn’t have to go. And Nigel Thornberry had left them back to Cusco tomorrow. When she gave her a walk so she makes noise in Nigel Knows Best.
• Bim (voiced by Greg Ellis), a Koala whose British accent and befriended by Eliza, Darwin, & Donnie.
• Shango (voiced by Bradley Pierce), an African Elephant who Eliza first met.
• Phaedra (voiced by Jane Wiedlin), a female African Elephant who appears in the episode, Forget Me Not, and who Eliza and Darwin were riding at the beginning of The Wild Thornberrys Movie.
• Zita (voiced by Andrea Thompson), an African Elephant who was Rebecca’s daughter and the mother of Shango, from the episode, Forget Me Not.
• Mali (voiced by Christina Pickles, an African Elephant who was Zita's aunt and Phadera's daughter, when Eliza helps her.
• Juka (voiced by Marquise Wilson) leader of the Massai legend between his wise Grandfather Makai (voiced by Courtney B. Vance & replaced by Steve Harris)
• Ben (voiced by David Gallagher)
• Franz Fensterkopt (voiced by Bronson Pinchot)
• Dr. Jomo (voiced by Brock Peters), a police officer who is a friend of Nigel Thornberry.
• Sri Mayasandra (voiced by Alan Henry Brown), a scientist who had found Donnie in the TV special.
• Baru (voiced by Cara DeLizia), a young Proboscis monkey who helps Eliza get back to her family, and his father, Baduk (voiced by Dwight Schultz).
• Lugan (voiced by Maureen Quinn), who was in the TV special.
• Saiful (voiced by Pamela Adlon), which was in the TV special. and Adlon voiced Tano, a Cheetah Cub who Eliza tries to help find and who she, Darwin and Donnie help try to find his mother in the episode, Cheetahs Never Prosper.
• Shi Shou (voiced by Dionne Quan), a baby panda, and Mei-Mei (voiced by Bai Ling), a mother panda.
• Conal (voiced by Michael Gough), a Hawk, and her wife Brianag (voiced by Laraine Newman).

• Candi Milo as Emily, a female wombat from the episode, Chew if by Sea.
• Susanna Voltaire, Russi Taylor, Melissa Fahn are Anna, Igna, and Katrina
• William H Macy as Skoot, a male reindeer who Eliza raced with in On the Right Track.
• Bill Fagerbakke as Dank, a black reindeer who appeared in On the Right Track.
• Cree Summer as Rosie, a "teenage" asian elephant.
• Georg Stanford Brown as Kito, the leader jaguar from the episode.
• Danny Cooksey as Wanuug, a polar bear who appeared in Polar Opposites.
• David Ogden Stiers as Karroo, an Aye-aye.
• Ron Fassler, Anne Lambton, & Jimmie Wood are Tak a little rat, Sheeba the eye patch wearing cat, & Bone, the three legged dog who helped Eliza find the Bangaboo in The Great Bangaboo.
• Marion Ross as Rebecca, an elephant whom Eliza saved in Forget Me Not. She was originally saved by Nigel from poachers many years ago. At the end of the episode, the elephant dies of natural causes which makes Eliza cry after she passes away and her daughter Zita takes over the herd.
• Robert Morse as Jake, a male tortoise who Eliza helped in Two's Company.
• Phyllis Diller as Samantha, a female tortoise who Eliza helped in Two's Company.
• Kelly McGillis & Peter Onorati are Winema and Pava, the leader Gray Wolves that appeared in the episode, Pack of Thornberrys.
• Chris Demetral as Mato, a Gray Wolf who apppeared in the episode, Pack of Thornberrys.
• Bill Brochtrup as Collin, a Common dolphin who Eliza swam with in the episode, Hello, Dolphin!.
• Jane Goodall as Herself, appears in the episode, The Trouble With Darwin.

Common Sense Media gave the series a rating of 5 stars, praising it for its ability to encourage young viewers to be empathetic toward animals, to want to find out about other cultures and ways of life, and to understand the vastness and diversity of the world.[20] Knight Ridder called the series "sympathetic".[21] The Native Voice complimented the series on its commitment to fun, adventure, detail, accuracy, and honesty.[22]