Nat Faxon Captain Underpants, Mr. Krupp Voice Jay Gragnani George Beard Voice Ramone Hamilton Harold Hutchins Voice David Koechner Mr. Meaner Voice Tress MacNeille Ms. Hurd Voice Laraine Newman Ms. Tara Ribble Voice Stephen Root Mr. Morty Fyde Voice Jorge Diaz Melvin Sneedly Voice Mindy Sterling Melvin's mom Voice Erica Luttrell Erica Wang Voice Dayci Brookshire Jessica Gordon Voice Evan Kishiyama Steve "Gooch" Yamaguchi Voice Lewis Black Ragely J. Snarlingtooth Voice Tom Wilson Major Messy, Camoflush Voice Sean Astin Narrator Peter Hastings Executive Producer Mark Banker Writer Kevin Peaty Director John Matta Writer Daniel Domínguez Writer Seung Woo Cha Director Jeff D'Elia Writer Todd Grimes Director Erik Kling Director