Cujo (also known as Ghost Dog) is a small ghostly dog that appeared in the episode Shades of Gray. Though seemingly harmless, he can change from a cute little puppy into an enormous, rabid, dog monster.
Nicktoons: Globs of DoomEditCujo is a boss in Nicktoons: Globs of Doom. Cujo also got infected by the orange goo and headed towards the Axion Labs. Tak and Beautiful Gorgeous then battled Cujo and after they beat him he ran into a wall and the goo from him got spilled all over Cujo.
Nicktoons: Toons WarsEdit
Cujo appeared as mini-boss in Nicktoons: Globs of Doom. When the heroes arrive at Axion Labs Valerie becomes very mad at Cujo and attacks him and Cujo gets mad. Cujo then transforms into a giant monster and they battle him. After they battled him he turns back into a cute little dog.