- "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.
HistoryMany 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. 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.
- Annoyingly Cute Triplets Who Lived Upon the Hill (mother and aunts)
- Monty Uno A.K.A. Numbuh 0 (elder son)
- Benedict Uno/Father (younger son)
- Mrs. Uno A.K.A. Numbuh 999 (daughter In-Law)
- Numbuh 1/ Nigel Uno (grandson)
- DCFDTL (adoptive grandchildren)
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.
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.
In addition to his demonic heritage, Grandfather possessed several other superpowers similar to his son, Father, but are much more advanced and even a few that his son does not have. His powers are likely genetic as he passed most of his abilities onto his son, Ben. It appears that he got his abilities from his grandmother.
- Citi Zombification: He had the ability to turn people into Senior Citi-zombies; monstrous, geriatric undead who could turn others into zombies as well, through their touch. Although people turned into Senior Citizombies did retain a semblance of their personality, they invariably became the obedient minions of Grandfather and attempted to transform anyone they came into contact with, whether human or animals.
- Reality Manipulation: Grandfather could warp reality to an extent as he was able to turn many KND treehouses into Tapioca Factories as well as being able to affect inanimate objects, and made them Victorian Era in appearance.
- Fire Manipulation: He has the power to manipulate fire. His powers over fire are much more advanced than his son.
- Energy Projection: He showed the power to project heated energized blast form his eyes as well as his hands.
- Telekinesis: He has telekinetic abilities similar to father himself.
- Electrokinesis: There would be electrical surges when he was angered
- Shape-Shifting: Like father, he too can shape-shift.
- Levitation: Like father, he too can levitate as seen when he was leading his Senior Citi-zombies.
- Supernatural Strength: He has a degree of superhuman strength, being able to break through tons of metal which he was buried beneath.
- Invulnerability: Not even "39 gazillion tons of red hot metal and duct tape" was able to crush him or even hurt him at all.
- Immortality: This anti-aging is also proven by the fact that he has been alive before the Victorian Era and has lived to the dawning years of the 21st century.
- Decommissioning: However, his mind is his weakness, as erasing his memories makes him forget the fact that he even has great demonic powers. This makes him a clueless & completely harmless old man.
- Hope: By Grandfather's own admission, he said that as long as children had hope (which is the only thing more powerful than him), they would be able to rebel against him,
- 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 at least forced Ben 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.