"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!!"
Benedict Wigglestein ("Grandfather") Uno, Sr. is the main villain 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 by far the most powerful villain in the series.
Long ago, Grandfather ruled the world 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, defeating 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, every nearly KND operative (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.
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)
One of the ACTWLUTH is possibly to be his mother
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. Grandfather's power also affects inanimate objects, making them green-tinted and Victorian in appearance.
In addition, Grandfather possesses several other superpowers similar to his son, Father, such as control over fire, 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.
- One possibility is that the weapon Monty used on him was based on information about decommissioning technology within the Book of KND.
- 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 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 overall design resembles that of Aku from Samurai Jack.
- Grandfather's large, beaky nose is not visible when his face is shown from the front.
- Unlike Father, Grandfather's mouth is visible at all times.
- Grandfather's sons and grandson were among the only characters to never be turned into Senior Citizombies.
- Numbuh 1 and Sector Z are the only people to be seen to be totally immune to Senior CitiZombification, the they were seen touching the zombies and remaining normal. This implies that they will be the future heirs to Grandfather's powers. Though it's possible that the process is triggered by the Citizombies actively grasping their victims, so direct physical contact alone is insufficient. (Though the hamsters being infected after attacking a senior-citizombified Numbuh 5 make this unlikely)
- He is the only villain that can defeat the KND since he can turn them into Senior Citi-Zombies, but the KND fighting him alone would be hard
- It is unknown if Count Spankulot,Common Cold,or Chad Dickson. are affected by zombification. Common Cold could be affected, if zombification is not biochemical based. It is likely so, since he is shown senior citizombified along with most of the other villains. Since Count Spankulot seemed to be fleeing from the zombies and/or Grandfather, it's possible that he could be affected too. Chad could probaly be turned into one but he was seen escaping the covention center
- It is possible that Grandfather was once part of the KND (6th age maybe?), since he is affected by decommissioning and recommisioning.
- He 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 have a major victory over all of the KND, albeit however temporarily.