GrandFather

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. 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.

History
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 other son, Benedict Uno, 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 saying he liked his other son more.

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.

Powers
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.

Role in Ultima
In Ultima, GrandFather was revived once more by Padro Lodo, who took the precaution of draining 1/3 of Grandfather's powers and handing them over to Maleficent so that the old demon sorceror would be unable to betray the Organization and try and overthrow Maleficent. Grandfather now serves as Father's commanding officer, having been granted the ability to summon heartless from his own dark energies, and is also a high-ranking villain in the Org's ranks.