* Peter Hatcher: The narrator of the story, Peter is a thoughtful and responsible older brother to Fudge. He often finds himself frustrated by Fudge's antics but loves him deeply.
* Fudge Hatcher: A mischievous and energetic four-year-old. Fudge is the source of much chaos and humor in the story, always getting into trouble and causing his family to worry.
* Tootsie Hatcher: Peter and Fudge's younger sister. Tootsie is a sweet and curious baby who often becomes a target of Fudge's mischief.
* Sheila Hatcher: Peter, Fudge, and Tootsie's mother. Sheila is a loving and patient mother, but she can also be exasperated by Fudge's behavior.
* Dad: Peter, Fudge, and Tootsie's father. Dad is a supportive and understanding father who often helps Sheila deal with Fudge's antics.
While these are the main characters, other important characters appear throughout the story, including their grandparents, friends, and the family's pet turtle.