The villains of the Kids Next Door, lead by Father, join forces to resurrect the Ultimate Evil, Grandfather, a tyrant who once ruled the world many years ago when most of the villains were themselves kids. However, Father disgraced him that he can't even try to destroy the KND and the Villains were quickly betrayed when they are turned into Senior Citizombies, creatures that are immortal and can transform any living creature into one of them and slaves who are forced to make Tapioca to refuel Grandfather so he can find and destroy the Book of K.N.D.
Ben Diskin
as Nigel 'Numbuh 1' Uno / Hoagie Pennywhistle 'Numbuh 2' Gilligan Jr / Numbuh 101 (voice)
Lauren Tom
as Kuki 'Numbuh 3' Sanban (voice)
Dee Bradley Baker
as Wally 'Numbuh 4' Beatles / Mr. Fibb / Toilenator / Joaquin / Tommy Gilligan (voice)
Cree Summer
as Abigail 'Numbuh 5' Lincoln / Former Numbuh 11 - Cree Lincoln (voice)
Jason Harris
as Chad Dickson (voice)
Grey DeLisle
as Crazy Old Cat Lady/Gramma Stuffum (voice)
Jeff Bennett
as Mr. Boss / Mr. Fizz / Benedict Wigglestein (voice)
Jennifer Hale
as Fanny 'Numbuh 86' Fulbright / Computer (voice)
Mark Hamill
as Stickybeard (voice)
Tom Kenny
as Knightbrace / Mr. Wink (voice)
Maurice LaMarche
as Father (voice)
Matt Levin
as Patton 'Numbuh 60' Drilovsky (voice)
