Captain Underpants / Mr. Krupp / Buffalobe (voice)

Harold Hutchins (voice)

George Beard / Young Mr. Cleveland (voice)

Narrator / Putter Mulligan (voice)

Jessica / Dressy / Smartaconda (voice)

Melvin / Stanley Peet (voice)

Benjamin Franklin (voice)

Comic Narrator / Marlin (voice)

Steve "Gooch" Yamaguchi (voice)

Mr. Meaner (voice)

Mr. Cleveland / Viper Chai (voice)

Erica (voice)

Miss Anthrope (voice)

Bo Hweemuth (voice)

Lee Dingman / Hugo Mouthingwad (voice)