Diablo is the main antagonist of the 1983 animated film, Goose Hollow, and its 2017 animated television remake series of the same name.
In "Releasing the Demon Lord", after the Abominable Snowman emerged from the book, the spellbook (that had previously thrown in the cave) suddenly unlocked, and Diablo was released from the it. Once the cat-like demons Scud and Peppers returned with Jake finally kidnaps Darwin in an attempt to kill the boy, Diablo revealed himself. Upon realizing that Diablo intended to take world full of monsters, Diablo promptly take over the world by turn into a post-apocalyptic and bizarre world, vowing vengeance upon his parents' abuse. He released the Lawn Gnomes from their manuscripts as a distraction and then drove off with the other manuscripts. Diablo proceeded to release the other monsters from the spellbook and turn all the humans into demons so that Diablo could avenge his mother and his father. The released monsters quickly wreaked havoc, destroying a section of the town in the process. Diablo took over the local television station, having his minions freeze the officers into icy blocks.
Lorraine later arrived at the television station to contact the authorities, but was instead met by Diablo. Lorraine offended Diablo by referring to him as a "monster leader", prompting Diablo to have her frozen by the aliens. Afterwards, Diablo released the rest of the monsters from the manuscripts and ordered them to find Jake so he will make him a enemy. The monsters lay siege to a nearby high school, where Jake is furiously typing a new story from his typewriter in order to trap the monsters in them. Diablo personally confronts and betrays Jake, reminding him that they share a consciousness and that they had once been friends and revealing his betrayal at having been locked away for so many years. When Jake still attempts to suck him back, Diablo breaks Jake's fingers with the typewriter.
In "The Last Confrontation", Jake lured the monsters away from the road by driving a bus down the road. Diablo ordered the monsters to destroy the bus and kill Jack and Darwin, but upon stopping it, they found that it was filled with dynamite that promptly exploded, temporarily destroying the monsters. This bought Jake and the young human boy some time to an abandoned amusement park, followed by Diablo, who could read Jake's thoughts. Upon arriving at the amusement park, Diablo released the final monster, The Blob, which quickly consumed Jake, but Diablo noticed that Jake didn't had the powers. Darwin fled to the top of a Ferris wheel, pursued by the monsters. Darwin managed to open the book just as the monsters reached them, and when promptly opened it, the impact causing a vortex to appear that began to suck all the monsters (including Scud and Peppers) into the book. Diablo, in a final attempt at revenge, grabbed Jake and began strangling him, but Darwin kicked him, sending Diablo flying into the vortex, cackling madly until he finally vanished inside. Diablo makes his final vow of revenge, calling out to Jack, "See you in your dreams!", but Diablo reveals that he replaces with a clone to prevent from being re-imprisoned, furiously flies into the cave, kidnaps Darwin.
Diablo threatens to eat Darwin, but the orphanage's dog, Meg, arrives to stop the ruthless demon and the fight begins afterwards. When Jake reach to the cave to save Darwin, Diablo is about to scare and attack Meg and Darwin but Jake and Dragon came to rescue from him. Rigby then comes to the scene and fought Diablo. Meg and Darwin escapes out of the cave but Diablo attacked Rigby and the two of them fell deeper into the cave. Meg dragged Darwin out of the cave and to safety, but Diablo grabbed Jake and dragged him back into the cave. Jake and the demon begin to fight each other and Diablo was winning until a stake fell down towards the demon, who was unaware of this as he was too busy attacking Jake. Diablo's wing was impaled by the stake and gave a screech of pain, and fearfully tries to escape, but accidentally hits the stone, sending Diablo to falling to his death into the purple river of goo, but not before the stake fell down towards his heart.
Diablo is usually a mean, evil, cunning, manipulative, ruthless, treacherous and a bit short-tempered dream demon.
- In the deleted scene, Diablo represents Eric Idle's dark side.
- Diablo did not make an appearance near the beginning of his respective show until the third season. This was most likely a way to surprise the audience that he is the main antagonist and not the Showman.
- Diablo is similar to Ratigan from The Great Mouse Detective in many ways:
- Both are revealed to be murderers. Syndrome killed a dozen superheroes to get rid of competition, and Ratigan drowned several widows and orphans as revealed in the song "The World's Greatest Criminal Mind".
- Both have a famous nemesis. Diablo's nemesis was the once-famous villain, Jake before he retired, while Ratigan's nemesis is Basil of Baker Street, the famous mouse detective.
- Both trap the heroes before heading out to carry their evil plan.
- Both kidnap a young child before trying to escape (Darwin Dawson for Diablo; Olivia for Ratigan).
- Diablo shares some similarities to Madame Medusa from the Disney film The Rescuers. They both kidnap an orphan for their own selfish reasons: Penny for the Devil's eye, Darwin Dawson for his cheap money. They both try to kill the film's protagonists (Diablo succeeds in killing Big Fat Man), they are both verbally abusive to their captors, they both have bumbling henchmen, and both are finished off by crocodilians.