The main character, a six-year-old bunny.
- Bears Are Bad News: He once pretends to be a fierce bear.
- Brought to You by the Letter "S": His overalls have an "M" on them.
- Cheerful Child: While he does get angry sometimes, he's generally a positive, upbeat character.
- Feud Episode: He and Judith temporarily end their friendship in "The Big Fight". He's the one who brings them back together.
- Fully Dressed Cartoon Animal: Wears a shirt, overalls and shoes.
- Gosh Dang It to Heck!: When he calls Judith a dummy, it's treated like he'd sworn.
- Height Angst: Sometimes, he takes offense at being called little and/or wishes he was taller.
- Jerk with a Heart of Gold: More emphasis on the "heart of gold" part. He is far from a jerk...he's more like a sweet little boy with a very slight mean streak.
- "Just Joking" Justification: Twice, he has made fun of Judith and said, "but I was just making a joke."
- Kindhearted Cat Lover: He likes all animals, cats included, and he's a nice little boy.
- Limited Wardrobe: Mainly wears his yellow shirt and red overalls.
- Mr. Imagination: Likes to play make-believe games.
- Nature Lover: He seems keen on learning about nature and cares about the environment.
- One Episode Fear: His fear of bees takes up one episode.
- Playing Sick: In "Milo's Sore Tummy", he didn't really have a sore tummy. He just pretended to.
- Potty Failure: In "Shame", he wets his pants in class and that's the reason for the titular shame.
- Puppy Love: He once got a crush on Daphne. It seems to run in the family because both his parents had crushes when they were his age.
- Take a Third Option: When he wonders whether to use the blue or yellow pencil, he eventually decides to take the red one instead.
- Fully Dressed Cartoon Animal: Wears a sweater, pants and shoes.
- Good Parents: He seems to be a reasonable, good dad along with Vanessa.
- Happily Married: "The Argument" aside, he and Vanessa seem to have a happy marriage.
- Mr. Imagination: Seems to enjoy playing pretend games almost as much as Milo.
- Nature Lover: Seems keen on camping and concerned for the environment. He seems to like astronomy, too.
- Out-of-Character Moment: He shouts that he's leaving Vanessa in "The Argument", despite normally being levelheaded and cheerful.
- Puppy Love: When he was six years old, he got a crush on a girl named Louise.
- Fully Dressed Cartoon Animal: Wears a dress, leggings and shoes.
- Good Parents: Is a kind and hardworking mother, raising her son well along with George.
- Gosh Dang It to Heck!: When she says, "Oh, darn", it's treated as if she'd sworn.
- Limited Wardrobe: She always wears a pink dress with a purple flower on it, and purple leggings.
- Puppy Love: She got a crush on a boy named Paul when she was six.
A girl in Milo's class, who is his best friend.
- Best Friend: She and Milo are best friends.
- Cheerful Child: Despite being a bit gloomy when she's angry or afraid, she's generally a happy kid.
- Feud Episode: She and Milo fall out in "The Big Fight".
- Fully Dressed Cartoon Animal: Wears a dress and shoes.
- Limited Wardrobe: She always wears a blue and purple dress.
- Ms. Imagination: Likes playing make-believe as much as Milo.
- Toilet Humour: She once drew a peeing dog as a joke.
- Why Did It Have to Be Snakes?: She appears to be afraid of spiders.
The unnamed teacher of Milo, Judith, Thomas, Vincent, Daphne, Roger, Elise and one other.
A boy in Milo's class, who is a bit of a handful.
- The Bully: Zigzagged. He can tease a lot but isn't sadistic.
- Cassandra Truth: When he tells Milo and Judith not to feed the animals at the zoo, they think he's just being a spoilsport and making up rules, but it turns out to be an actual rule.
- Jerk with a Heart of Gold: Likes to tease, but stops if things get too serious.
- The Prankster: Judith once noted that he'll never stop pulling pranks.
A boy in Milo's class.
- The Prankster: Not as much as Vincent, but he is a bit mischievous, liking to play the odd prank now and again.
A girl in Milo's class.
A girl in Milo's class.
- Does Not Like Men: Initially, she disliked boys because of her mean brother but now she likes boys fine.
- Girlish Pigtails: Has blonde pigtails.
- Hair of Gold, Heart of Gold: Once she got over not liking boys, she became a nice girl, and she's also blonde.
- In-Series Nickname: "Lisa".
- Limited Wardrobe: Always wears a blue dress with a white apron.
- Shrinking Violet: Subverted. She was shy in her debut episode but is now no longer shy.
- Sibling Rivalry: She and her brother don't get along too well.