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)