"Thank you, son! Thank you for reawakening the pure evil that lay dormant within me for these many years...And now, get out of my sight!!"

– Grandfather's first words as a villain to Father

Grandfather is the main antagonist of Operation: Z.E.R.O.. He is a demonic being who ruled the world before being overthrown by his son Monty Uno aka Numbuh 0. Many years later, he is revived by his other son and successor Father and begins transforming the people of the world into Senior Citizombies. Grandfather is very tall and lanky, and significantly taller than a normal person. He has a bald head and a large beard with long, scraggly strands of hair. Despite making only one appearance, Grandfather is the most powerful villain in the series.


Many years ago, Grandfather ruled the world with an iron fist and forced all children to work in his tapioca factories. One day, his son Monty Uno discovered the Book of KND and led an uprising of children. They had defeated his evil father, erasing his powers and memories.

Grandfather transforming Toiletnator into a Senior Citi-zombie.

Years later, Grandfather's younger son, Benedict Uno aka Father, used the Recommissioning Module on Grandfather, now a decrepit old man, to restore his former self, expecting to work together with him to destroy the Kids Next Door and rule the world alongside him. Instead, Grandfather shuns his son and orders him to leave, calling him a failure, and only awakened him just because that the fact that Father could not destroy the "irksome" Kids Next Door by himself. He then said that he liked his other son more anyways even if he had destroyed his powers, making his only loyal younger son leave his side.

He then revealed his plan: To turn all the kids in the world into Senior Citi-Zombies, as well as everyone who has ever been a kid. The villains cheer, until they realize that they all used to be children and that this amounts to every person in the world. They try to flee, but in vain; Grandfather turns all of them into his zombie minions and orders them to invade the Kids Next Door's treehouses throughout the world, turning them into zombies as well and turning the treehouses into tapioca factories. Soon, nearly every KND operative (every kid in town and Gallagher Elementary School and presumably every person) on the planet has been transformed, save for Numbuh 1, who would soon re-commission his father, Numbuh 0.

After establishing his rule over the world, Grandfather turns his efforts to finding and destroying the Book of KND, as it could provide children with hope; the only thing that could defeat him. He arrives near its location just in time to be confronted by his son Monty, who is carrying the book in his back pocket. Monty by wrestling with him until he found the Book of KND. He is able to resist Grandfather's power, but soon begins to succumb to it.

He is able to fight off Grandfather long enough for Sector V to launch the KND Moonbase at him, seemingly destroying him. However, Grandfather survives this relatively unscathed and emerges from the wreckage, only to find out that he is standing in a Decommissioning Chamber from the moon base. Grandfather and Numbuh 0 are then both decommissioned once again, turning them back into their harmless, clueless adult selves.



Grandfather had no remorse for any of his actions. He betrayed all of the other villains, who were willing to help him, without a second thought and turned them into Senior Citizombies along with the KND. He is also shown to be extremely selfish, wanting the entire world for himself simply so that he can have solitude and tapioca pudding, and making the citizombies loyal only to him.

Despite his evil intentions, however, he is shown to be fond of his elder son, Monty (when he's not directly opposing him). Grandfather showed sad disappointment towards the non-evil life his son chose to have. Before Grandfather's decommissioning at the end of Operation Z.E.R.O., it was revealed that despite Monty's rebellion years ago, he was still in Grandfather's will.

Compared to his younger son, however, Grandfather was extremely disappointed with Ben and viewed him as a disgrace and a coward, despite Ben following in his footsteps. He was not pleased nor excited to see him again after his recommissioning, as Ben had not recommissioned him out of love for his father but only so that he could finally defeat the KND.


You... Big... JERK!!

Father's reaction to Grandfather's cruelty

On top of this, he was not impressed and grew annoyed when Ben points out that unlike Monty, he grew up to be pretty evil, and blasts him in order to make him shut up.


Grandfather has the ability to turn people into Senior Citizombies, monstrous, geriatric undead who can turn others into zombies as well, through touch. Although people turned into Senior Citizombies do retain a semblance of their personality, they invariably become the obedient minions of Grandfather and attempt to transform anyone they come in contact with, thus allowing them to rapidly spread. Grandfather's power also affects inanimate objects, making them green-tinted and Victorian in appearance. He can use telekinesis and even shape shifting.

In addition, Grandfather possesses several other superpowers similar to his son, Father, such as his shadow suit, levitation and physical invulnerability. He also appears to be immortal while he has his powers, since not even being crushed by "39 gazillion tons of red hot metal and duct tape" damaged him visibly.


  • Grandfather was reawakened using the Recommissioning Module, despite not being a member of the Kids Next Door. This implies that he was defeated in the past by a decommissioning device, despite the KND (7th Age/Futuristic that is) not even existing prior to his defeat.
  • Operation: C.A.K.E.D.F.I.V.E. involves the Annoyingly Cute Triplets Who Lived Upon the Hill, who were enemies of the KND during the nineteenth century. Father refers to the mother of the ACTWLUH as his great grandmother, which would make her Grandfather's Grandmother and one of the triplets is his mother. It is shown in Z.E.R.O. that Numbuh 0 was the founder of the 7th age of the KND and the 19th century was a totally different age.
  • Grandfather's large, beaky nose is not visible when his face is shown from the front.
  • Grandfather's second rise and fall were both made possible by his sons; Father (Benedict Uno) recommissioned him and Numbuh Zero (Monty Uno) decommissioned him.
  • Unlike Father, Grandfather can fly, and his mouth is visible at all times.
  • Grandfather's sons and grandson were among the only characters to never be turned into Senior Citi-zombies.
  • As Numbuh Zero destroyed the recommissioning module and Grandfather did not show gratitude to Father when he recommissioned him, it is unlikely that he was ever recommissioned. However, it is implied that he regularly pays his son Monty Uno a visit when he does not have his powers.
  • Grandfather is the only villain that has not engaged a member of Sector V (Numbuhs 1-5) personally. He is also the only villain to be decommissioned. Furthermore, he is the only villain to actually defeat the KND organization (a Senior Citi-zombified Numbuh 362 personally declares the end of the KND to Grandfather), though he ultimately does not destroy the Book of KND.
  • Judging by Father's words during Operation: I.T., it is likely that Grandfather forced his sons to eat broccoli at some point in the past.
  • Grandfather's overall design resembled Aku from Samurai Jack. 
  • If you type in Grandfather on the rainbowmonkeys.com website, it says inexact. It appears that the galactic kids next door is not aware of him. 
Community content is available under CC-BY-SA unless otherwise noted.