A 5-year-old inquisitive and imaginative boy who loves his hamster and is a fan of the (fictional) Blue Sox baseball team. He also likes Captain Brainstorm because he comes up with great ideas. He enjoys going to preschool, although he misses Elephant, but he is still happy. He is known as Little Bill because his actual name is William Bill Glover Jr; his father's name is also Bill.
Elephant is a small light yellow hamster who loves Little Bill. The only noises that are heard from him is his blinking eyes after Little Bill has spoken and he sneezes in one episode. When the rest of the family goes on vacations, he is left alone with Alice the Great, Little Bill's great-grandmother. He gets sick in one episode, but gets better at the end.
The oldest of the Glover children. She is a highly talented basketball player on the school team, and also at basketball camp, where she won a trophy and is also in a choir practice. She is often seen getting bossy. (She sometimes argues with Bobby.) She is the only sister.
Bobby is the most studious of the kids. He is always reading and investigating things. He is the middle child and oldest son of the Glover children. He can also play the violin and sometimes he can say upsetting things, usually resulting in his family saying, "Bobby!"
Father of Bobby, April and Little Bill. They have a very close relationship with their father. He works for the Department of Housing, as a housing inspector. His hobby is collecting and listening to jazz records. He is also known as Big Bill because his actual name is Bill Sr.
Great-Grandmother of Little Bill, Bobby, April and Jamal; Alice is also Brenda and Deborah's grandmother (see "The Magic Quilt"). Alice the Great has an older brother and older sister (see "The Surprise") and a cousin who lives in Cincinnati. Usually teaches Little Bill lessons and tells stories to him. She also lives with the family.
Captain Brainstorm is an astronaut who has an orange rocket and an orange space suit. Little Bill is a fan of his TV show, Space Explorers. Captain Brainstorm has a dog called Spark-E whose tagline, "Ruff-Roo!", is in a dog accent.
Andrew is a 5 year old white, red haired, freckled boy who is Little Bill's best friend. Andrew and Little Bill have many things in common - they both like Captain Brainstorm or play with construction sets, etc. In one episode Copy Cat Little Bill and Andrew and a quarrel and Andrew called Little Bill a copy cat, but soon learns his lesson and apologizes to him. Andrew has a pet dog named Farfy. Andrew is sometimes seen with his cousins: Kevin (13) and Rachel (11).
Kiku is an 5 year old Asian-American friend of Little Bill's. Little Bill would say that she is the nicest of his friends. She loves nature (particularly flowers) and origami (her grandmother, Ms. Notsuko, showed Little Bill how to make origami in the episode "Shipwreck Saturday"). Although it is never shown in the series, it is implied that she and Little Bill may have a small crush on each other.
Classroom friend of Little Bill (see "New Foods" and "Natural Root Pals"). Teaches Little Bill about experiencing the Spanish lifestyle by inviting him to dinner. Dorado introduces Bill to arroz con guandules y platanos(chicken with rice and bananas). Dorado is a bit of a comedian and is 6 years old.
Grandson of Alice the Great's best friend Emmaline, uses a wheelchair to get around because he was born with cerebral palsy. He and Little Bill are good friends and pretend to be dinosaurs together; Monty's favorite is the triceratops. Monty is 5 years old.
Little Bill's teacher, who later marries Dr. Winthrop Clinkscales. (but the students are still allowed to call her Miss Murray, since they have trouble pronouncing her husband's name). Their engagement was mentioned in "The Ring Bear" and they were married in "Miss Murray's Wedding". She is 22 years old.
A Hawaiian lady, with a cat named Sophie. She was Little Bill's neighbor but then moved back to Hawaii, in the episode "Same Moon, Same Sun, Same Star," to live with her sister Mimi. She is 56 years old.
Mr. Rojas is an old man who speaks English and Spanish. He moved into Mrs. Shapiro's house and met Little Bill in the episode "The New Neighbors." He has a dog called Lito who's good at doing tricks. He only appears in "The New Neighbours", "Doggie Magic", "The Early Bill", and "The Halloween party." and is 65. He has children, but they're all grown up and have families of their own.
A music store owner only seen in "The Musical Instrument". He is a talented musician and shows little Bill the piano, accordion, saxophone and drums (which happens to be his grandson's favorite instrument). He is 63 years old.
She is April's best friend, also in basketball camp and the choir. She is a little older than April. She was seen and mentioned in the same episode, but she was sick in that episode so she had to be taken home and miss her choir class. Little Bill replaced her in the choir.