Long ago in the last days of the Age of Chaos, when the Old Ones first created lesser beings to serve their whims in defiance against TOWIAA, the planet Eltar was among the early worlds forged by their struggles, with the newly created inhabitants coming to be known as Eltarians. Like most other early races during the Great Chaos, the Eltarians were made as toys for sport in the Chaos battlefield, and so came to view the Old Ones as their worst enemy.
However, there was one Eltarian who saw the Ancient Ones as not a foe to oppose, but rather a benefactor to worship for good favor. His name back then was unknown, but everyone nowadays knows him best as the Master Vile. To gain the favor of the Ancient/Old Ones, Vile became a necromancer, a sorceror with the ability to raise the dead, by studying tomes of eldritch lore that the dark gods had left behind for unsuspecting mortals to read as a cruel courtesy. It was through these tomes that Vile first found out about the Old Ones' leader, Chernabog, and how he was split into different incarnations of himself across the Great Chaos, with the closest incarnation to Eltar being Octomus The Master. Vile soon began using his necromantic abilities for chaotic means in service to Octomus, hoping one day to be noticed for his cruel endeavours. He was only mildly inconvenienced when the Old Ones were pushed away by the New Gods and the Lands of Legend truly came to being with their combined help, but Vile did not care. All that mattered was that Octomus must be called upon and soon if the glorious chaos was to restart quicker.
Eventually, it came to pass that the planet Eltar discovered new sister planets with alien races of their own that had been forged by the coming of the Lands of Legend, and their king so desired to develop good relations with those worlds in order to unite the M51 Quadrant in perfect balance. Vile, on the other hand, simply saw this as an opportunity to call upon like-minded beings like him over to his side in worship to the Great Evil. The names of these fellow worshippers are unknown to this day, having been lost to the ravages of time. With an army of dissenters at his side, Vile began preparations to call upon Octomus through an arcane ritual which would allow him to ascend into full demonhood and join the ranks of the slowly returning Old Ones. At last, the day came when Eltar came into alignment with the Negaverse planet Nemesis, and the resulting beam of unlight shone down on the site of Vile's ritual, where he had by now forcibly stabbed himself with several shards of Dark Energon in several key spots on his body and glowing from the unlight of the eclipse, all while his cult worshippers chanted in the name of Octomus and Cthul'hu. But before Vile could gain ultimate power and become a god, his ritual was interrupted by the intervention of Eltarian General Zordon and his Royal Guard of Rangers, who attacked his worshippers and knocked him out of the site of the elcipse beam. With the ritual incomplete, the dark energon shards having received insufficient dark energy to fuel the complete transformation, Vile instead mutated into his current monstrous form and attacked Zordon in rage over his defiance, but little did he realize that the ritual had been partially successful after all.
Attracted by the ruckus Vile was causing in his anger, an avatar of Octomus appeared to Vile and offered him the chance to retaliate against the Royal Guard as a reward for all his good work in his name. Vile, elated that his satanic prayers had been answered, agreed to the terms and was subsequently endowned with enough magic to complete the transformation only so much as to make him a Daimaou, a Great Demon King according to early Yamato mythology, but it could not reverse the monstrous mutation inflicted upon himself. Nevertheless, Vile became strong enough to repel Zordon and his men, but still they lived and were able to escape for future battles, much to his displeasure. However, Octomus' avatar was quick to reveal another catch to the deal made with Vile: Lord Chernabog had been sending out invitations for many dark warriors to join in him for the coming battle with New Gods of Order and Light, and Vile, by way of signing the contract with Octomus, had gratefully accepted the invitation, which meant he was now stuck in servitude to the Great Evil whether he liked it or not. But Vile didn't care, nothing else mattered anyway; he gained the power necessary to conquer worlds, and he was all too eager to utilize that power as often as he wished.
Octomus thus sent Vile on his first mission to aid the Japanese Abomination, Aku, in attacking Edo with an army of mythological Echthros known as the Yokai. The Eltarian was allowed only one fleet of starships to bring to Japan, but he could at least comission as many ships as he wanted, just as long as they did not change the course of history on that world. Vile agreed, and immediately boarded his flagship to meet up with the demon wizard for further instructions. Along the way, he discovered the world of Hsskhor, a jungle world of lizard-folk set in the Mesozoic era, and conquered it just for extra measure to secure the services of its primitive inhabitants, the Saurians. In exchange for not killing them all, Vile forced them to begin worship of the Great Evil, to which they, in their warlike attitude, agreed all too eagerly. However, the Saurians' neighbors, the Dall Fae, a race of fae descended from the Third Race of Avalon, opposed the whole idea and sought to free their world from Vile's forces. To make a long story short, they failed, and they were punished severly by being forced into slavery, with their Queen being seduced and forced into union with Vile in order to one day produce the Witch Queen Bandora, nicknamed Rita, and the Undead Prince Gasha Dokuro, nicknamed Rito.
The Keyblade Wars - X
(takes on both his Black Cross Fuhrer and Emperor Aton forms as the 10th Seeker of Darkness, before meeting his end in during the Keyblade War at the blade of Revan)
Birth of A New Era
(Is shown to be pulling himself together in his current Daimaou form, and is a member of the Separatists)