Monty Uno is the father of Nigel Uno. In Operation: Z.E.R.O., he is revealed to be Numbuh 0, the founder of the modern KND Organization (the 7th Age of the KND), as well as the older brother of Benedict Uno, (a.k.a. Father). He is the adoptive uncle of the Delightful Children From Down The Lane.
He wears a red plaid shirt with green overalls. As a kid he wore black shorts, red vest and tan undershirt.
Numbuh 0 has probably tasted the "Fourth flavor" since he said after being recomissioned "I have a hankering for some blurpleberry ice-cream - it's the closest thing to the fourth flavor I've ever tasted!" Numbuh 0's brother, notably the villain Father, was probably named after Benedict Arnold, both being traitors.