Appelox was one of the 6 Holy Titans of Harmony (Magic, Kindness, Generosity, Loyalty, Laughter, and Honesty), who created Equestria and the Elements of Harmony themselves. But after 7000 years of harmony between ponies and Titans, Appelox, the Holy Titan of Honesty, succumbed to overwhelming hunger, betraying its brethren and devouring them, growing stronger in the process. The last one standing in Appelox' way, Twilus the Holy Titan of Magic, gave birth to Princesses Celestia and Luna to take care of Equestria in the Titans' absense, then placed a protective seal around Equestria too strong for him to breach before getting eaten as well.
Role in the story
Once alternate (fanmade) versions of Equestria start appearing, the hungry leviathan sets his sights on them and begins gobbling them up whole, gathering the strength he needs to breach the protective barrier around the original Equestria and devour it in turn.
By eating the apples that exist in the PONY.MOV version of Equestria, Jappleack has the ability to project her consciousness into what used to be the Titans' world, now Appelox' domain. This displeases Appelox greatly, therefore he tries to warn her to stay away by sending its cruel sons to ravage her world, and when she persists he sends her to the canon Equestria, the apples wherein do not trigger the reaction that sends Jappleack into Appelox' void anymore. However, Twilight Sparkle (canon) is aware that alternate dimensions are disappearing and that Jappleack has something to do with it. To get to the root of the problem, she manages to synthesize PONY.MOV-apples artificially, allowing Jappleack to visit Appelox' realm once more. The furious Titan finally reveals itself to her to try and terrify her away, allowing Jappleack to warn Equestria of the impending danger.
The ponies are mortified when they find out the power of the threat they must face, and have no idea what to do against an entity superior to the Elements of Harmony themselves. But Jappleack insists that since Appelox is made of apples, she can eat him. The canon ponies admit that, no matter how insane, this is probably the best plan they have. Empowered by the dozens of universes he consumed, Appelox finally breaches the barrier Twilus placed on Equestria and prepares to devour the realm, but Applejack launches Jappleack at him using a swing. Jappleack opens her mouth impossibly wide and bites Appelox' head off, releasing the essence of the Holy Titans entrapped in its gut and putting an end to the traitorous abomination's hunger once and for all.
- Appelox bears some resemblance to The Hungry Hungry Caterpillar, protagonist of Jappleack's (and Applejack's) favorite book.
- Appelox' design may draw some inspiration from a Gyarados, a serpentine Pokémon (specifically the Shiny version of said Pokémon, which is red).
- Appelox' goal of consuming all worlds may be a reference to Unicron.