Characters played by Nat Faxon
Captain Underpants
Mr. Krupp
Buffalobe
Characters played by Jay Gragnani
Harold
Characters played by Ramone Hamilton
George
Young Mr. Cleveland
Characters played by Sean Astin
Narrator
Putter Mulligan
Characters played by Dayci Brookshire
Jessica
Dressy
Smartaconda
Characters played by Jorge Diaz
Melvin
Stanley Peet
Characters played by Todd Grimes
Benjamin Franklin
Characters played by Peter Hastings
Comic Narrator
Marlin
Characters played by Evan Kishiyama
Steve 'Gooch' Yamaguchi
Characters played by David Koechner
Mr. Meaner
Characters played by Phil LaMarr
Mr. Cleveland
Viper Chai
Characters played by Erica Luttrell
Erica
Characters played by Patty Mattson
Miss Anthrope
Characters played by Brennan Murray
Bo Hweemuth
Characters played by Nolan North
Lee Dingman
Hugo Mouthingwad