as Captain Underpants / Mr. Krupp (voice)

as Harold (voice)

as George (voice)

as Narrator / Mr Gigglenose (voice)

as Jessica / Dressy (voice)

as Mr. Ree (voice)

as Melvin / Stanley Peet / Melvin's Dad (voice)

as Comic Narrator (voice)

as Steve "Gooch" Yamaguchi (voice)

as Mr. Meaner (voice)

as Erica / George's Mom (voice)

as Miss Anthrope / Harold's Mom (voice)

as Bo Hweemuth (voice)

as Diddlysaurus / George's Dad (voice)

as Melvin's Mom (voice)

as Creepy Rattlechains (voice)

as Mayor Hoppy McChapper (voice)