Cujo is a small ghostly dog that appears in the episode "Shades of Gray" Though seemingly harmless, he can change from a cute little puppy into an enormous, rabid dog monster.


Shades of Gray

Cujo is the ghost of a guard dog for Axion Industries. He came back to the human world in order to reclaim a squeaky toy he had left in the dog kennels. Cujo first appeared at Danny's school and, after transforming, ran off to Axion Industries, with Danny in hot pursuit. Danny's attempts to restrain him only led to the lab being destroyed (resulting in Valerie's father losing his job). Danny attempted to throw Cujo back into the Ghost Zone, only for the dog to escape again. He then began trying to tame Cujo, but the pair was attacked by Valerie, outfitted with her new ghost hunting equipment. Danny finally managed to locate the ghost dog's squeaky toy and Cujo happily gained liberation.


Cujo is just a dog and does what dogs do: bark and play. However, since he's a ghost dog, his aggressive anger can be unlimited and very ferocious if he's provoked in any way.

Cujo is always happy but also very cautious when he wants to be. He had a strong sixth sense and can tell whether a ghost is strong or not.


Cujo it's a ghost dog with red eyes a purple tongue sharp teeth a black nose and wears a black flea collar with some gray spikes. His collar also has an Axion Labs logo on the tag.


Danny Phantom

Cujo viewed Danny as a 'master' or 'friend' since Danny is the one who found him and has thus been interacting with him. At first their meeting started off rocky as Cujo's continuous search for his missing toy caused several disruptions in Danny's life as well as the life of Valerie Grey, who would go on to begin hunting them and other ghosts as a result. The two ghost-beings managed to bond during Danny's attempts to train him, only to find the dog has already been trained (during his life as a guard dog for Axion Labs). Cujo seemed to greatly enjoy the attention given to him by his new halfa friend and continued to return to the human world, presumably to seek out Danny. It is unknown whether Danny regularly visited his new ghost 'pet' or if Cujo followed his 'master' everywhere.

Danny mentioned in "Fanning the Flames" that he desired a puppy in his younger years but was forbade to own one by his parents. His joyful interactions with the ghost dog (primarily while in his smaller form) show that he does enjoy the animal's company. Sam admitted that the two are sweet together, though their ghostly attributes also make their interactions "freaky."

Valerie Gray

Cujo unintentionally began Valerie Gray's hatred for ghosts and Danny Phantom when he destroyed her father's workplace while looking for his toy buried beneath the lab, costing her father his job. He continued to appear in several places where she is in the same vicinity as Danny, leading her to believe he was deliberately attacking her (he may have been tracking her as well due to her connection to Axion Labs). Cujo may hold a personal grudge against Valerie as he does become violent when in her presence, tearing apart her lunch bag without provocation and growling at her menacingly, though there is not much proof or motive for this theory.

After these constant attacks continued to ruin her life, Valerie takes up ghost hunting weapons and attempted to eradicate both the dog and the ghost boy who she thought was connected to his attacks.

Powers and Abilities

  • Intangibility, Invisibility, Flight: As a ghost dog, he has the same powers that all ghosts have.
  • Passing through the Fenton Portal: Cujo is the only ghost seen to be able to pass through the Fenton ghost portal even when it was closed.
  • Transformation: Whenever Cujo is upset, he transforms himself (unconsciously) into a big, powerful, savage, and almost unstoppable dog with amazing strength that destroys everything in his path. Upon seeing Danny, he becomes relaxed and happy, returning to his normal and harmless form. When he is transformed, his normal abilities are increased and his tail also becomes green fire.
    • Enhanced Strength: When Cujo is transformed, he becomes very strong and capable of bending metal, taking down titanium doors, and ripping out trees from their roots with incredible ease. Even when small, he can drag Danny around with ease.
    • Enhanced Stamina: When transformed, he is more durable than any normal human or dog.
    • Enhanced Resistance: When transformed, his body is more resilient to damage than any human or living dog.
    • Enhanced Speed: When transformed, he is faster than a normal dog.
  • Teleportation: He can teleport himself from one place to another at will, like he did when he appeared in the basketball game and when he disappeared after recovering his toy.
  • Sixth Sense (apparently): He can tell whether a ghost is strong or not.
  • Enhanced Senses: As any dog, his senses of smell and hearing are beyond normal human limits. He also may have night vision like other dogs.
  • Invisibility
  • Intangibility
  • Cujo passing through the Fentons' portal
  • Cujo transformation
  • Cujo ripping out a tree
  • Cujo running
  • Teleportation
  • Teleportation
  • Teleportation
  • Cujo dragging Danny
  • Cujo speed


Season 1

Season 2

Season 3


Ghost dog nicktoons globs of doom

Ghost dog in Nicktoons: Globs of Doom

  • Cujo also appeared in Nicktoons: Globs of Doom as the boss for Amity Park, being controlled and infected by the Morphoids-like blob.
    Ghost dog nicktoons globs of doom 2

    Ghost dog in Nicktoons: Globs of Doom 2

  • In the game Nicktoons: Globs of Doom, Danny called Cujo "Ghost Dog."
  • Danny's choice of calling the ghost dog "Cujo" is a homage to the deadly dog from the movie Cujo, made famous by Stephen King.
S01e10 Cujo necklace

Cujo's collar

  • Cujo seems to be wearing an Axion Industries dog tag, a possible indication that he was one of Axion Industries' guard dogs and was drawn there to look for his chew toy in the area. This has lead to fan theories that he may have been put down.
  • Unlike other ghosts in the series who typically oppose Danny, Cujo adores him.
  • Cujo is one of the very few ghosts who appears to have made a cameo in "Phantom Planet" turning Earth intangible.