During the events of "The Long Weekend", the wood Sprites living in the Pine Barrens revealed to Jake a prophecy about the Jersey Devil. According to the stars, once every hundred years, a great evil would rise from the woods and attack the Sprites for seven consecutive nights. The Jersey Devil would raid their crop supplies and pillage their food storage, which would leave them to starve during the winter. The stars also reveal that a hero would appear every one hundred years to defeat the Jersey Devil and restore peace to the Sprite village.
The Jersey Devil had a very peculiar look. It had the body of a brown moose and a lion tail. Its head was covered in grey fur and its eyes glowed a deep red. It also had a pair of short, rounded antlers on its head and a pair of grey eagle wings.
Since it was often described as a bipedal creature, the Jersey Devil could stand on its two hind legs just as easily as a human. It could also use its two front pincer-like hooves just like hands. It could fly very high thanks to its wings and often enveloped itself with them to camouflage its body in the foliage of the forest. As seen very briefly, it hasd a sensitive nose (if hit in that area, it would most likely flee). The Jersey Devil could not speak and only came out at night.
The Jersey Devil was a very intelligent creature. When fighting the American Dragon, it often managed to counterattack Jake's moves. It could use the surrounding environment to its advantage and even lured Jake into his own trap. The Jersey Devil was very cunning, and would stop at nothing to deliver its rampage.
The Jersey Devil was caught in a net and thrown off a steep cliff. It was unclear whether it survived or not. However, due to the Sprites' prophecy, a Jersey Devil should return after another a hundred years to restart its rampaging cycle.
- It was voiced by Dee Bradley Baker.
- The Jersey Devil's cry was a mix of roars and screeches.
- Jake's father, Jonathan, mistook the Jersey Devil for a bear.
- The Jersey Devil could be affected by the stunning effects of bear spray.
- Fu Dog and Lao Shi never mentioned the Jersey Devil in the entire series.
- The legend of the Jersey Devil inspired the name of New Jersey's NHL ice hockey team, the New Jersey Devils.
- When Jake hit the Jersey Devil on the nose, the creature's screeches sounded like a dog's.
- In cryptozoology, the Jersey Devil was described to be a winged half bird, half horse, standing upright on hoof feet with a reptilian tail, and to a hairy creature walking on all fours, resembling a cross between a monkey and a dog.