- "The One-Horned Diablo is a unique, deadly creature. It will eat any living thing, but prefers humans and snarks. The Diablo is a shape-shifting species, able to take on the form of whatever it has eaten. If spotted, do not kill it. There is only one of its kind, currently held in captivity at Troop HQ in Lakewood, USA."
- ―The Troop official site's description of the One-Horned Diablo
300-400 feet (original design)
The One-Horned Diablo is a unique monster which can take the shape of anything it eats.
According to Hayley's Troop profile, the One-Horned Diablo was captured while trying to eat an old lady.
It is briefly seen in its cell in Troop HQ.
The One-Horned Diablo will eat any living creatures, but prefers Snarks and humans.
The One-Horned Diablo's body is mostly scarlet. Its head is large and round, with a fang-filled, worm-like mouth, brown ridges around the mouth, and a curved, white horn protruding from the right. Its right arm is clawed and made entirely of wood, with a mouth and large, round eye on a stalk on the forearm. Its left arm is a large pincer with two mouths, and the rest of its body is serpentine with three mouth on its torso and tail.
The One-Horned Diablo's body is an orange color. Its left arm has two crater-like mouths, and a large pincer, and a dark-red eye on a bright-grey stalk on its wooden right arm. It has a large, round head with a fang-filled, large, round mouth, and a curved, white horn protruding from the right. It also has a vine-like torso that ends in a large mouth with fangs and a serpent-like tongue.
The One-Horned Diablo can either shapeshift into, or gain the intelligence and abilities of any living creature it eats.
- According to Hayley, the One-Horned Diablo was captured while trying to eat an old woman.
- As the One-Horned Diablo is the only one of its kind in existence, it is presumed to be either a unique monster, or the last of its species.
- Being a unique monster, the One-Horned Diablo is just like Dr. Cranius.