Judith "Judy" Moody is the main character of the Judy Moody series.
- Stink - Judy's idiotic little brother. He reads encyclopedias a lot and knows about everything. He owns a toad named Toady for the Toad Pee Club.
- Kate - The mother of Judy and Stink and the wife of Richard.
- Richard - The father of Judy and Stink and the husband of Kate.
- Grandma Lou - Judy and Stink's grandmother. They go to see her every summer.
- Opal Moody - Judy and Stink's aunt and Richard's sister.
- Rocky Zang - Judy's best friend.
- Frank Pearl - Judy's "pest" friend.
- Jessica Finch - Judy's classmate who is a good speller.
- Amy Namey - Judy's classmate whose name rhymes like Judy.
- Mr Todd - Judy's teacher.
- Tori - Judy's pen pal from England. She has everything that Judy never has: many sleepovers, a phone, a washcloth, and pounds of allowance. She is a big fan of Bonjour Bunny.
- Laura Chumsky - An little girl in a wheelchair who has had a heart replacement. She is getting a hamster when she goes home. She is given a doll that looks just like her, like the newspaper said.
- Chloe - A college student. She calls her friends "peeps".
- Hannah - A girl who comes to see Judy's cherry pit in Judy Moody Gets Famous!.
- Ricky - Hannah's little brother. He eats Judy's cherry pit because he thinks it's an M&M.
- Mrs Grossman - A teacher who teaches Class 3G while Mrs Todd is in Italy. She gives treats for good behavior or good work and has a tent at the back of the room called the Attitude Tent. Judy is briefly not keen on her. Mrs Grossman appears in Judy Moody Goes to College.
- Zeke - Stink's teenage friend who is the president of the BBA (Bigfoot Believers Association). He appears in Judy Moody and the Bummer Summer.
- Herb - A member of the BBA.
- Rose - A member of the BBA.