Nat Faxon
Captain Underpants / Mr. Krupp (voice)
Jay Gragnani
Harold (voice)
Ramone Hamilton
George (voice)
Sean Astin
Narrator / Mr Gigglenose (voice)
Dayci Brookshire
Jessica / Dressy (voice)
Clancy Brown
Mr. Ree (voice)
Jorge Diaz
Melvin / Stanley Peet / Melvin's Dad (voice)
Peter Hastings
Comic Narrator (voice)
Evan Kishiyama
Steve "Gooch" Yamaguchi (voice)
David Koechner
Mr. Meaner (voice)
Erica Luttrell
Erica / George's Mom (voice)
Patty Mattson
Miss Anthrope / Harold's Mom (voice)
Brennan Murray
Bo Hweemuth (voice)
Kevin Michael Richardson
Diddlysaurus / George's Dad (voice)
Mindy Sterling
Melvin's Mom (voice)
Stephen Tobolowsky
Creepy Rattlechains (voice)
Kari Wahlgren
Mayor Hoppy McChapper (voice)
