On screen
Cast
12 credited performers
Nat Faxon
Captain Underpants / Mr. Krupp (voice)
Jay Gragnani
Harold (voice)
Ramone Hamilton
George (voice)
Peter Hastings
Garg (voice)
Sean Astin
Narrator (voice)
Secunda Wood
Moxie Swaggerman / Xemio (voice)
David Koechner
Mr. Meaner / Mr. Nearme (voice)
Nolan North
Dr. Shifty Fitzgibbons / Jett Wingman (voice)
Gary Anthony Williams
Dupe Licitous (voice)
Jorge Diaz
Livmen / Stewart / Statrew (voice)
Erica Luttrell
Arice (voice)
Laraine Newman
Elbrib (voice)