Big Brother is a giant teenage villain based on the common archetype of the abusive older brother. He first appears in Operation: M.I.N.I.-G.O.L.F. where he is defeated by Numbuh 2. In Operation: M.O.V.I.E., Big Brother apprehends Numbuh 4 when his disguise is blown. In Operation: Z.E.R.O., Big Brother's giant pants are on display in the KND museum. Big Brother Doesn't Function with the Teen Ninjas probably due to his size and only functions with adult villains.
- Big Brother's name comes from George Orwell's book 1984, although he is completely different from the Big Brother in that story.
- This character may have been inspired by the villain Solomon Grundy from DC comics.