Chubbo and the Ghost Hamsters are a group of deceased hamsters that once worked as the power supply source for Sector V's tree house. Their only appearance was in Operation: G.H.O.S.T. when Chubbo had recently died, which lead the Sector (except for Numbuh 4) to having a funeral for him in Nigel's backyard, where they buried him. He, along with the other ghost hamsters, appeared that night in the Treehouse and kidnapped Numbuh 3, taking her underground, where all the ghost hamsters live (like a hamster heaven).