Played by: Austin Dilulio
- Adaptation Personality Change: Although Timothy's personality hasn't changed that much compared to how he was in books. In the original book he is a lot more sensitive and can be seen crying. He's actually wished Claude would mess up or make a mistake, including wishing he would fall into a pile of mud or a puddle. In the later release of the book with newer illustrations and his portrayal in the Yoko & Friends series and the animated series, this side of Timothy remains.
- In the Yoko & Friends book "The Halloween Parade" he tells Muriel with a grin about The Franks' Halloween costume◊ and mentions "real blood" making Muriel scared about Halloween much to Yoko's dismay. This side of Timothy is never seen in the TV series.
- Cheerful Child: Always focuses on the positive side of life.
- Companion Cube: A toy penguin named "Pengy."
- The Everyman: Probably to represent a few school children that are nice and helpful with other students and parents.
- The Hero: When ever a major or minor problem happens with a student. He always finds a way to solve their problem.
- The Leader: Of the Type V II Variety, though Yoko took this role in the "Yoko & Friends" books.
- Nice Boy: One of the nicest characters in series along with Yoko and Lilly.
- Sensitive Guy and Manly Man: Timothy is a lot more kind and nice compared to Claude.
- Stock Audio Clip: Whenever Timothy gets amazed or surprised, he says "wow!" which is repeated several times throughout the series.
Played by: Lisa Yamanaka
A sweet-natured Japanese cat who plays the violin and is very close to Timothy.
- Affectionate Nickname: Her mother calls her "cherry blossom."
- Breakout Character: Since 1998, Yoko has gotten her own series of books and is one of Rosemary Wells's most beloved characters. Yoko is also one of the only characters created by Wells to gain two book series. The rest of the characters such as Timothy, Charles, Nora, Fritz and Doris were only featured in one book prior to her debut in 1998, which marks the second appearance of Doris and Timothy.
- Break the Cutie: Poor Yoko has gotten this three times in the show.
- Cartoony Eyes: This is only present in the series, while in the original books Yoko's green pupils are a lot bigger and looked more cat like.
- Cheerful Child: She's one of the kindest students in Hilltop School.
- Cute Kitten: Mainly due to her mannerisms and how innocent she is compared to the other students.
- The Cutie: One of the nicest characters in the series along with Lilly and Timothy.
- Disappeared Dad: Although we do see her grandfather a few times in the show. In the book "Yoko's Paper Cranes" we do see her grandma and grandpa during a flashback when she used to live in Japan when she was very little. In the same book, while not seen it does mention her father while she and her mother are moving to America.
- Distaff Counterpart: Yoko is basically a cat version of Timothy, except being Japanese.
- Expy: Of Violet from the original book.
- Heroic BSoD: After she witness her taketombo getting broken, Yoko starts to cry quietly and can't even respond when Mrs. Jenkins asks her if she'd like to hear a story.
- The Heart: Yoko's fits this trope to a T due to her kind and non-mean or aggressive behavior unlike some of the students.
- In the Yoko & Friends Book "The Halloween Parade" she is seen holding Muriel's hand during Halloween.◊ Muriel herself is a toddler aged kitten like Yoko.
- The Ingenue: This is especially notable in the 2011 book "Yoko's Show-And-Tell" and the 2014 book "Yoko Find Her Way"
- Japanese Politeness: Along with her mother
- Limited Wardrobe: While the rest of the students are seen wearing the same clothes. Yoko gets a special mention since in the episode "Yoko". Her own wardrobe contains the same set of shirts and clothes she wears to school. Except in this adaptation, she wears a red dress with a yellow skirt instead of her red dress with white flower polka-dots in her book appearances. Yoko is also mostly seen with all her buttons covering her yellow dress but in the books she is only seen having one button with her yellow skirt exposed.
- Naïve Everygirl: Due to her being from Japan, she is unaware that not everyone likes sushi as seen in the episode "Yoko".
- Nice Kitten: She's one of friendliest characters in the show and even the books.
- OOC Is Serious Business: While Yoko is one of the only characters who never gets angry or mad with the other students, in the first episode after Timothy gets pushed by Claude trying to catch the football to prevent it from hitting her, she gets mad and shows disgust while saying Claude is arrogant and thinks he knows everything.
- Performance Anxiety: This only happens in the episode where the class are doing their musical performance in front of their parents.
- The Pollyanna: Always focuses on the positive sides of life along with her friend Timothy.
- Supporting Protagonist: She is best friends with Timothy, the title character. However, she is the main protagonist of Yoko and Friends, a book series that could be considered an Alternate Continuity.
- Tender Tears: In the episodes "Yoko" and "The Taketombo". Thankfully these instances are the only times she is brought to tears during the series.
- Title Character: Of the second episode and the original 1998 book version.
- Token Minority: Pretty much the only kid part of a different (and confirmed) ethnicity. (Besides Juanita who is a Mexican but she only appeared in two episodes)
- Vocal Evolution: Lisa Yamanaka previously voiced Wanda Li from The Magic School Bus back in 1994. When she voiced Yoko, her voice sounded more older due to Yoko's voice actress starting to hit puberty at the time of the show's original run.
Played by: Laurie Elliott
Timothy's intelligent badger or skunk friend who sometimes knows even more than the teacher, but tends to be messy.
- Bungling Inventor: One of his inventions didn't work, and it got him down.
- Freaky Is Cool: He likes insects.
- Put on a Bus: In "Fritz on the Move."
- The Bus Came Back: He returns in "Many Happy Returns", only one episode later, though it takes place after a vacation.
- The Smart Guy
- Stage Magician: Serves this role with Lilly as his assistant in "The Talent Show"
- Wise Beyond Their Years
Played by: Max Morrow
A shy little mouse who finds it hard to talk in front of others, but has a great imagination. He mostly plays with Timothy, Yoko, and Lilly.
- Character Development: After "Shy Charles", Charles starts talking more and even becomes very helpful with Lilly, helping her remember certain things.
- Cowardly Lion: Is very timid and quiet but when Timothy (the only member of the class who had bothered to reach out to play with him) got locked in the janitor's closet, Charles immediately jumps into action, pulling the emergency alarm and summoning Mrs. Jenkins for help.
- The Cutie: Can you blame his aunt for thinking this in the beginning of "Shy Charles"?
- Height Angst: In "Measuring Up", Charles suffers a bit of this when Claude calls him a "shrimp" after everyone takes their measurements and he's found to the shortest in the class. Doris cheers him up by telling him that she's the tallest at school, but the shortest in her family and inviting him to play with her at her place after school. Later, Charles chastises one of Doris's brothers when he calls her a "shrimp."
- Mr. Imagination: He's often shown to be one of the more imaginative students during play.
- The Quiet One: For the first few episodes, until "Don't Lose It Lilly" when he starts becoming more vocal around Lilly and helping her remember certain things.
- Shrinking Violet: He later grows out of this in later episodes.
Played by: Alyson Court
A noisy mouse who earned the nickname Noisy Nora who tends to be a bit bossy and sulky. Nora enjoys her mother reading her stories. She has a baby brother named Jack and a sister named Kate that's about 3 years older than her. She owns a pet lizard named Norman who later in the series moves to Hilltop School in order to live in a bigger aquarium. She is also one of the very first characters created by Rosemary Wells.
- Abhorrent Admirer: To Timothy in "The Greatest", if only because she became overly-reliant on him and made him do everything for both her and others when anyone had the smallest problem.
- Affectionate Nickname: Her mother calls her "sugar snap."
- Bratty Half-Pint: She also used to be mischievous as seen in the Noisy Nora book.
- Characterization Marches On: Compare her personality in the show to her original appearance in the original Noisy Nora book. She was a lot more mischievous and annoyed her parents than how she acts in the show.
- Cute, but Cacophonic: She may be cute like Charles but she sure can make a lot of noise and yells a lot.
- Middle Child Syndrome: This is toned down a little in the show when in the original Noisy Nora book. She tries so hard to get her parents attention that she ends up making her home a mouse and making loud noises.
- The Napoleon: She doesn't get that concerned with her size, unlike Charles. But she did mention that when she was scared of dinosaurs since she thought all of them were huge. This is understandable since she and Charles are the smallest students in the class, and seeing a huge dinosaur from her point of view can be very intimidating.
- No Indoor Voice: This is also another reference to the book Noisy Nora where Nora came from.
- Those Two Girls: With Lilly
- Vine Swing: Does this in the racing episode, complete with her yelling like Tarzan
- Why Did It Have To Be Dinosaurs?: She gets over it when she finds out that not all dinosaurs are huge.
Played by: Mag Ruffman
A forgetful and air-headed fox who is often seen with a ribbon tied around her finger so she remembers things. Lilly moved to the neighborhood recently from somewhere down south and has her first snow day during the series. She eventually becomes best friends with Nora.
- Ascended Extra: Lilly is featured more often in the series compared to her appearances in the original books.
- Berserk Button: While generally sweet and cheerful, you don't want to give her anything with mustard on it!!
- Break the Cutie: While very brief, she can be seen crying when she realizes that she thought that she forgotten her pet goldfish Treasure. Until her mother tells her that she's cleaning the bowl.
- Cloud Cuckoolander: Subverted, she may not be the brightest but really cares about her friends and her pet goldfish.
- Cute Clumsy Girl
- The Cutie: She has a cute laugh sometimes snorting like a pig when she gets excited or happy.
- Disappeared Dad
- The Ditz
- Does Not Like Spam: She doesn't like mustard or strong peppermints because they burn her tongue.
- Forgetful Jones: She claims that the reason she's so forgetful is "That her head is full of sunshine." according to her mother.
- Lilly's forgetfulness is taken more seriously in "Lifesaver Lilly"
- Hidden Depths: While she is very forgetful, she always remembers to feed her pet fish Treasure...well most of the time that is.
- The Ingenue
- Kindhearted Simpleton
- The One Who Wears Shoes: She, Mrs. Jenkins, and Fritz's mother are the only characters on the show who wear shoes.
- The Pollyanna: She hardly gets angry minus her reaction to getting mustard in the episode where Doris tries to be friendly around her.
- Simpleton Voice: A rare female example, but this goes away when she get's very upset, annoyed, or sad.
- Spell My Name with an "S": Although episode titling and other official resources clearly indicate that her name is "Lilly," the spelling is so unusual that it's regularly misspelled on the Internet as "Lily" and it's not at all unusual to see both spellings in pages about the series.
- Those Two Girls: With Nora
- Vocal Evolution: In the episode "Lifesaver Lilly", Lilly's voice sounds more serious and monotone. This is due to the episode taking her forgetfulness more seriously since she really wants to take care of the class pet. This is most notable when she tells herself that she really is too forgetful to take care of their pet even though she always remember feeding her pet fish...sometimes that is.
Played by: Tracy Ryan
A boisterous beaver who likes sports and is the tallest in the class, but the smallest in her family.
- Abhorrent Admirer / Hopeless Suitor: Seemed to be an implied one for Timothy in the first episode, but it was dropped afterwards.
- The Big Girl
- Genki Girl
- Huge School Girl
- Outnumbered Sibling/The One Girl: She is the only girl child in her family while her siblings are boys.
- Pink Means Feminine: Inverted. She wears a pink dress but she's not really feminine.
- Tomboy: She is sporty, not afraid to get dirty, and likes to play soccer with her older brothers.
- Took a Level in Kindness: Like in the "Yoko & Friends", she is a lot more tolerable than her debut in the 1985 book "Hazel's Amazing Mother" where she can be seen tearing up Hazel's doll. She was also a bully in that book until the end where Hazel's mother shows up and ends up apologizing to Hazel and makes it up by sewing her doll back together.
- Trademark Favorite Food: Seems to be squeeze cheese.
- Why Did It Have To Be Bugs?
Frank & Frank
Played by: Darren Frost (Frank #1) and Rob Stefaniuk (Frank #2)
Twin French bulldog brothers who love playing sports and playing pranks. They like to play together and often speak in unison.
- Book Dumb: Implied.
- Catchphrase: "Me before you, me first!" "No, me before you, me first!" "...Okay, we'll both go first!"
- Companion Cube: For Frank #2, a stuffed bulldog named "Bully"
- Dogs Are Dumb: Inverted; while not dumb, they aren't the brightest students. The same can't be said for their father.
- Gassholes: Averted. Despite loving franks and beans, they're never shown passing gas on the show.
- Furry Reminder: They like to drink from the faucet.
- Jerk Jocks: Can be somewhat like this at times.
- Kindhearted Simpleton: While mischievous, they actually care about the other students (Especially Yoko as seen by their reactions to breaking Yoko's taketombo) especially each other.
- This can't be said in at least one of the Yoko and Friends books, in which they are pretty much bullies.
- Leitmotif: They have one that generally seems to play whenever they're doing their "me before you, me first" routine, or otherwise goofing off.
- Missing Mom
- The Pranksters
- Single-Minded Twins
- Simpleton Voice
- Those Two Guys: They are an inseparable pair of twins who are almost always seen playing together and are partners for each class activity.
- Trademark Favorite Food: Franks & Beans
- Trickster Twins: Although they borderlined on being bullies in a Yoko and Friends book.
Played by: Joanne Vannicola
An arrogant raccoon who seems to be good at everything. He had a bit of a rivalry with Timothy at first but they soon became good friends. He is mostly seen with Grace.
- The Ace: But not at swimming. His revelation of this to Timothy helps mend bridges between them.
- Book Worm: Unusual for his character archetype, he's the one who is usually seen on his own reading a book
- Break the Haughty: While Claude thinks he's great at everything, he forgets that he can't swim and tells Timothy not to tell anyone about this. He even has to dunk inside Timothy's swimming pool to avoid seeing seeing any of Timothy's friends discover that he actually can't swim even though it's implied that he actually told some of the students about this.
- The Bully: To Timothy in the first episode only.
- Deadpan Snarker
- Missing Mom
- Pride: As shown the racing episode and the first episode where he meets Timothy.
- The Rival: To Timothy until he shows Claude how to swim in "Taking the Plunge."
- Smug Snake: In the earlier episodes he is always seen making this expression especially in the episode where he and Grace are racing and are proud of being in First place.
- Spirited Competitor
- Small Name, Big Ego
- Took a Level in Kindness: Toward Timothy after "Taking the Plunge." Helping Claude learn how to swim helped them become good friends.
- Vocal Evolution: In the episode where the students race. He along with Grace talk in a more monotone, deep, and mocking tone due to them focusing on winning instead of having fun.
- Why Did It Have To Be Water?: Until Timothy teaches him how to swim.
Played by: Linda Kash
A somewhat snobby upper-class cat who likes dancing, especially ballet and figure-skating. She is mostly seen with Claude.
- Alpha Bitch: Depending on the episode, but especially the racing episode with Claude.
- Break the Haughty: Twice, as first seen in the episode where she breaks her leg and begins crying. The second is the episode where hears Doris talking about how "funny" she looked when she fell down causing her to cry, which later results in an argument between her and Doris.
- Cats Are Mean: Subverted
- Deadpan Snarker
- Expy: Grace is very similar to the bunny character also named Grace from the original book complete with how close they both are with Claude.
- Girly Girl: She is upper-class, loves dancing, hates getting dirty and gross things, and likes things to be perfect.
- Tomboy and Girly Girl: The Girly Girl to Doris's Tomboy when they go to dance class.
- Jerk with a Heart of Gold:
- Neat Freak
- Pink Means Feminine: Her ballet outfit is pink and she is very feminine.
- Pride: Most notable when she's racing with Claude
- Took a Level in Jerkass: In the episode "Abracadabra", she takes a peek in Fritz's magic book and steals the talent for one of his tricks which causes him to get mad and blame Timothy.
- Took a Level in Kindness: She starts acting less mean and bossy once Juanita becomes a new student.
- Towards the end of "Abracadabra", she's horrified that Fritz and Timothy are no longer friends and eventually apologizes just because she can't stand to see them fighting.
- True Blue Femininity: She wears a blue dress and she is very feminine.
Played by: Susan Laney Dalton
A Spanish cat who just transferred to Hilltop School in the last two episodes and was a bit anxious about leaving her mother.
- Canon Immigrant/Canon Foreigner: Juanita was exclusive to the show, only showing up in the final two episodes. After the show ended in 2004, Juanita showed up in more of the Yoko & Friends books such as "Make New Friends"◊ and "The Halloween Parade"◊ which shows Juanita getting more used to life in Hilltop School.
- Cute Kitten: A Mexican kitten to be exact
- Gratuitous Spanish: While Juanita and her parents do speak English, they would sometimes drop in some Spanish words into their sentences.
- Last Episode, New Character: She serves as the main character in the final two episodes of the show.
- Naïve Newcomer: Even more so than Yoko.
- Shrinking Violet: She is very shy when she meets the other students and always wants to be with her mother.
- Sixth Ranger: She joined the class at Hilltop School in later books of "Yoko & Friends" and sometimes in the Yoko series.
- Spexico: Juanita is a Spanish cat. Although her home resembles the type of house you would find in Spain, the way her parents dress in the TV series and some of the books appears to resemble the style you would mostly see in Mexico. Juanita also mentions Mexican food such as churros and enchiladas.
Played by: Fiona Reid
Formerly Miss Abercrombie; Mrs. Jenkins is the class' fox teacher.
- Author Avatar: Of Rosemary Wells
- Catchphrase: "Quick sticks, children."
- The One Who Wears Shoes: She and Lilly are the only characters on the show who wear shoes.
- Team Mom: By virtue of being the main adult in the classroom.
Played by: Jamie Watson
A cheerful beaver who is the school's janitor and bus driver. He used to be Mrs. Jenkins' student as a child.
- Nice Hat: He has one that he wears sometimes when driving the bus.
A student teacher badger or skunk who sometimes appears to help out, or cover for Mrs. Jenkins.
Timothy's mother and father
Timothy's kindhearted and lovely parents. Timothy's mother really cares and loves his child and even explains certain situations he's in.
Yoko's sweet natured and kindhearted mother. A Japanese cat who formerly lived in Japan along with her daughter.
- Barefoot Cartoon Animal: In the show and sometimes in the books. However Yoko's mother is mostly seen wearing table in the books.
- Japanese Politeness: Along with her daughter Yoko
- Japanese Ranguage: Subverted and avoided in the show and books. She speaks perfect English but would mostly talk more slowly compared to Yoko.
- Limited Wardrobe: She is always seen wearing the same colored kimono in every appearance in the show while in the books she is seen wearing a different colored kimono.
- OOC Is Serious Business: While she is commonly seen happy and is never seen sad or angry, in the book "Yoko's Show-And-Tell" she actually gets stern with Yoko by telling her no in a more annoyed or disgusted tone due to Yoko's doll being sent by her grandparents which is made of glass. Unlike the episode "The Taketombo" where she isn't mad at The Franks for breaking the taketombo (Due to it being made of wood and easy to repair with glue). Yoko is afraid of showing the broken doll to her mother due to the glass being difficult to repair due to the size of it.
- Yamato Nadeshiko: A western example.
Mrs. Jenkins' unseen husband.