"A million deaths, or a billion deaths, each fresh soul will be a gift for my Dark Masters, that will grant me my ascension. Soon, your precious Existence will die, swallowed by fire and death. And you...you will be nothing more than a distant memory in the minds of a doomed universe."
-The Skeleton King to Blue Team before he "banishes" them, directly preceding the events of the Black Century.
The Skeleton King, also known as The Dark Puppet Master, was the evil, deceptive, and cruel Champion of the Dark Gods, the successor of Veigar and Bearer of the Dark Banner. The Skeleton King was infamous for his skills at manipulation, and for his engineering of the War of Deceit. The Skeleton King described himself as the Master Puppeteer, the Deceiver of Nations, the Dark Prophet, and the Destroyer of Worlds.
The War of Attrition was entirely a scheme of his own making, where he opened portals to the Void, through which his minions, The Reapers, passed through into Existence in massive numbers. The War inflicted great destruction, annihilating numerous star systems, and nearly collapsing Mundus and Aetherius. However, The Skeleton King met his end, not at the hands of Blue Team, but at the hands of the old god Chakravartin.
The conflict caused by the Skeleton King was so devastating that Creation itself would have been permanently and irreparably damaged. This resulted in the Dreamer Ehyeh's subconscious rewinding time itself and nullifying the effects of the "Black Century".
During World War I, an alchemist, puppeteer, and magician known as Isidor Franz living in Austria-Hungary was experimenting with chemical and magical weaponry to use against the Allied Powers. His means of creating these weapons were extremely unorthodox, and he would often visit dangerous or strange methods. From the very start, Franz had a dark heart, he was sadistic, fantasizing about all the fascinating ways to take lives. He made these visions reality through his experiments, being paid by the Central Powers to create weapons. Still this wasn't enough - the ambitious Franz desired to discover new methods to destroy the foes of his leaders to prove himself further.
He would perform seances and ancient, taboo rituals that helped him reach out to the darkness of the Void. There, he hoped to discover the ultimate means of destroying life. In his vigorous experiments, he fully crossed the barrier between reality and the mysterious dark of the Void. There, Franz discovered the terrifying Dark Gods, and almost immediately becoming tainted with the influence of the dark beings. Recognizing the alchemist's talent with magic and science, the Darks saw the potential in using him as a servant. It didn't take long for the alchemist to succumb to the temptations of the Dark Gods, and he agreed to serve them faithfully, the promise of eternal life, wisdom, and power too much for the scientist to refuse.
He was absorbed into the Void fully, body and soul, where he would be tortured, broken, and indoctrinated into a foul, evil being corrupted and polluted by the Dark Powers. His flesh was rotted away, and his soul was desecrated. Any morality he possessed was eradicated, replaced by sadistic fury. He remained in this state, chained in the Void for many years, until he was fully ready to take on the mission of the Dark Gods. He was gifted dark, powerful armor, a staff blessed by the Dark Gods, as well as a personal army, one of the strongest ever seen and created in Existence. This army was made up of sentient machines known as Reapers, synthetics of terrifying power created by the ancient and elusive Leviathans. The Darks then let their Champion loose upon Creation, giving him the task to prove himself by bringing about the apocalypse. The Skeleton King immediately began planning for the perfect strategy to unmake Creation. His first move was to resurrect the dead Lordgenome, and his Spiral forces. In what came to be known as the War of Attrition, he planned for Lordgenome's armies to attack the strongholds of the Sol Alliance indiscriminately, weakening resistance to the breaking point, followed by an overwhelming invasion by his armies of Reapers, and rampaging across what remained in a tide of death.
When the War of Attrition was drawing to a close, the Skeleton King saw his moment to act. The Spirals had caused massive damage to Earth and allied strongholds in the Sol System, but Blue Team was fast closing in on Lordgenome, and they were getting close to fighting the final battle on the Granzeboma, the Spiral King's mighty flagship. Blue Team had successfully breached all defenses of the Granzeboma, and they did battle against Lordgenome on the Granzeboma's command tower. Ultimately, the Spiral King was beaten down, and Blue Team was preparing to finish him off, putting an end to the war, or so they thought. At that very moment a dark portal opened upon the command tower, the Skeleton King stepping out, applauding the valiant efforts of Blue Team, and revealing his plan to them as well as Lordgenome. The Skeleton King told the galactic warlord about his resurrection, and he revealed that Lordgenome was nothing but a puppet, and a tool of the Skeleton King's plan. Lordgenome denied these statements, saying that he served no one. Lordgenome then attacked the Skeleton King, but the Dark Champion easily and effortlessly subdued the human. Right before sending him over the edge of the command tower of the Granzeboma, The Skeleton King stated to Lordgenome, "It is time to put you back in your place, Lordgenome...the dirt!" He then threw the human off the tower, but Lordgenome grabbed hold of the Champion's cape, and they both were cast off the tower.
The Skeleton King teleported mid-fall to his personal Reaper carrier, leaving Lordgenome to his presumed death. The Granzeboma imploded, creating a very large portal, from which huge amounts of Reapers began to pour through. Many other portals were opened, the Skeleton King's invasion beginning. This officially ended the War of Attrition, and began the War of Deceit. The Skeleton King sought allies to make his puppets as well. For this, he turned to the Martian Emperor, who was already in a bad relationship with his neighboring planet, Earth. The Skeleton King appealed to his anger, by convincing the Emperor to declare war on Earth. With this, the Skeleton King began a devastating two-pronged assault of Earth.
Unfortunately for him, at the same time, the extragalactic alien alliance known as the Andromeda Treaty made planetfall on Earth too, seeking diplomatic relations with the humans. However, unknown to them, war had already engulfed Earth. Treaty ships were caught in the crossfire of UNSC ships. In retaliation, believing that the humans had no intention of peace, the Treaty returned fire. The Skeleton King himself realized the potency of the aliens, and attempted to convince them to join his side. However, the aliens flatly refused (this was because the Treaty leaders had no intention of sharing power or bowing to any religion. As a result, the Reapers and the Treaty began to fight each other too. Shortly after this, Blue Team managed to board the Prime Reaper and confront the Dark Champion directly. However, after a brief showdown, it was revealed that the Skeleton King's powers far surpassed any of the Team's, and he used his power to hurl the heroes into a time warp set to reopen a hundred years later. With Blue Team gone, the Skeleton King believed victory was inevitable. This began the dreaded "Black Century".
During the early events of the "Black Century", the UNSC was completely destroyed within the first year. Not long after this, the Andromeda Treaty began to lose motivation to fight the Reapers. Their fleets were exhausted, and their resources slimming. In order to end the conflict, the Treaty leaders ordered the harvesting of Sol, Earth's parent star. With this, the resulting supernova incinerated the surface of all orbiting planets, including Mars. The Martian Emperor pleaded with the dark Champion to save his world from the supernova, however, the Skeleton King refused, stating "You have outlived your minor usefullness...I no longer need you, my friend." At this, the Emperor was both infuriated and horrified, as the supernova engulfed his planet and incinerated all life in a flash of light and fire. As for Earth, it was taken over by Reapers and promptly protected by large shielding pylons within the Reapers themselves.
Throughout the remains of the "Black Century", the Skeleton King continued to hunt down and attack human planets, while the Andromeda Treaty also engaged in their own invasions. Innumerable worlds were plunged into chaos, war and destruction, and countless billions of lives were lost across the cosmos. It seemed every day like the light of hope became dimmer and dimmer for the free peoples of Mundus. By the end of the "Black Century", Blue Team returned, and the Skeleton King was forced to worry about them once again. However, he had grown much stronger since the last time they met.
During the final days of the war, the Skeleton King decided to launch his final offensive, which he hoped would win the prize promised to him by the Dark Gods; the gift of Daemonhood. This offensive was to be the siege and destruction of New Equestria, a fortified planet settled by the Equestrians, who were among the final remnants of resistance against him. In this offensive, the Skeleton King hoped to sever the mortal universe's last connection to Aetherius, Princess Celestia. Unfortunately for the Dark Champion, Blue Team knew of this planned offensive and rushed to New Equestria to take part in the battle. The massing forces of Reapers also drew the attention of the Andromeda Treaty, and it wasn't long before Reapers, Equestrians, and Treaty forces all scrambled for dominance in the battle. The grueling conflict lasted days, but at the end Blue Team and the Equestrians managed to hold the planet if only because the Skeleton King's attention was split between them and the Treaty.
Suffering colossal losses including a Devastator-Class warship to Blue Team, the Andromeda Treaty were forced into a full retreat, engaging their slip-space drives to return the fleet to their capital, the planet Palaven in the Andromeda Galaxy. The Skeleton King, angered at their interference, ordered his Reapers to pursue the Treaty. Several Reapers opened massive dark portals, and Blue Team managed to follow undetected. They soon appeared in Palaven's orbit, where a war was already taking place in space between the Treaty and Reapers. the Skeleton King was here, fighting the Treaty's fleets, but he was losing the fight, for Palaven was extremely well defended. The Skeleton King feigned vulnerability and begged Blue Team for an alliance, convincing them that only together could they destroy the Treaty. In the interest of ending the conflict, the Team agreed and with the help of Reaper ships, entered Palaven's atmosphere and launched an assault on the Treaty's seat of power, The Palace of Unity. Thanks to Blue Team and a small force of Reapers making planetfall, many defending fleets chose to redirect their efforts down to the surface. This weakening of the planet's defenses allowed the Skeleton King to break through, and he ordered his Reapers to lay siege to the now vulnerable planet.
The Councilors of the Treaty were destroyed by Blue Team in brutal confrontations. Afterwards, Blue Team confronted the Skeleton King once again upon his Prime Reaper, one last time. However, the Skeleton King had successfully pleased the Dark Gods and was was in the process of ascension, gifted by the Darks the power of a daemon. He transformed, and beat each member of Blue Team to near death with magic and unholy might. The Daemonic Skeleton King triumphantly declared that the End of Days had come, and that he would destroy Aetherius and Anurel himself. He opened a portal, transporting himself away to Aetherius, where he prepared to accomplish his final goal to ensure the success of the Dark Gods; to battle Anurel and kill him.
Blue Team was taken to Aetherius by a frightened Mew, who pleaded with the heroes to gather their last strength to defeat the Dark Champion. When they arrived, they were nearly too late; the Daemonic Skeleton King was in the process of beating down Anurel. Victory might have been his, however the powerful Old Gods who had simultaneously been attacking Aetherius ensured this was not to be. The Daemon was about to deal the killing blow to the Divine God, but in that instant, Chakravartin the God of Order and Power arrived on the scene. Chakravartin came from behind the Daemonic Skeleton King, clasping the fetid skull in his mighty hand and sunk his fingers into the Dark Champion's head to the sound of a horrid scream, and plunged his holy blade straight through the Daemon's chest, killing him.
This ended the Skeleton King's threat to Creation forever, and the furious Dark Gods claimed his soul upon his death, the now immortal spirit forced to spend eternity in torture at the behest of his former lords.