The Lich King

The Lich King is the master and lord of the Scourge, which he rules telepathically from the Frozen Throne atop the Icecrown Glacier.

Kil'jaeden created the Lich King from the spirit of the orcish shaman Ner'zhul to raise an undead army to conquer Azeroth for the Burning Legion. Initially trapped within the Frozen Throne with Frostmourne, the Lich King eventually betrayed Kil'jaeden and merged with the human Arthas Menethil.

The Lich King is the titular antagonist of World of Warcraft: Wrath of the Lich King, and Wrathgate.

History
When Ner'zhul attempted to escape Draenor, he was immediately apprehended by the demon lord Kil'jaeden, who enacted the blood pact that Ner'zhul had sworn many years earlier. Kil'jaeden ravaged and destroyed his body, but kept his spirit alive and encased it in a block of ice from the Twisting Nether. Kil'jaeden granted him increased power, including that over death itself. Ner'zhul ceased to exist, and the Lich King was created.

Formation of the Scourge
The Lich King was sent to Azeroth through the Great Dark Beyond, landing in Northrend where the ice that encased him formed into the shape of a throne, The Frozen Throne. Here, he would begin the formation of the Undead Scourge and in the process weaken the world in preparation for the Burning Legion. This new army would not fall victim to the petty infighting that had caused the orcs to fail in conquering Azeroth earlier. Sent to watch over him were the dreadlords, led by Tichondrius himself. Within the Frozen Throne, the Lich King experimented with his psychic powers and enslaved the local indigenous life forms. The plague of undeath that came from the Frozen Throne transformed each of them into his undead servants. Thus, using his psychic and necromantic powers, he was able to conquer much of Northrend. As he devoured more and more souls, he only grew in power as the individual undead under his control gave him "much needed nourishment". Thus, his powers began growing at an exponential rate; a fact that the dreadlords were well aware of and kept a good eye on him.

The Lich King entered a war with the kingdom of Azjol-Nerub, whose ancient inhabitants were immune to his plague of undeath. The 10-year conflict known as the War of the Spider ultimately ended with the Lich King's first major triumph (while the Nerubians were immune to the plague, their corpses could still be reanimated). The Lich King was impressed by his enemy, however, and adopted Nerubian architecture for his own, as a testament to the Spider Lords' tenacity and age.

Having by now established control over most of Northrend, the dreadlords urged Ner'zhul to proceed with the agreed-upon plan to prepare the world for the invasion of the Burning Legion.

The Lich King then used his telepathy to reach out into Azeroth and summon any dark soul that would hear his call. Kel'Thuzad, a mage and a prominent member of Dalaran's Kirin Tor, answered his call. Kel'Thuzad was soon ensnared by the Lich King, faithfully serving him as the first of The "Cult of the Damned"; a cult that would worship the Lich King as a god and be taught necromancy to better aid their undead armies.

Kel'Thuzad and the dreadlord Mal'Ganis then were instructed to begin paving the way, but Ner'zhul, ever mindful of Kil'jaeden's schemes, secretly sought a way out of his prison...

Scourge of Lordaeron
After preparing for many long months, Kel'Thuzad and his Cult of the Damned finally struck the first blow by releasing the plague upon Lordaeron. Prince Arthas Menethil and Lady Jaina Proudmoore along with Captain Falric began Lordaeron's search for answers on the new threat. Lordaeron's northern most settlements were consumed utterly by the Plague.

As the ranks of the undead swept across Lordaeron, King Terenas' only son, Prince Arthas Menethil, took up the fight against the undead. As was the Lich King's intention all along, Arthas succeeded in killing Kel'Thuzad, but even so, the undead ranks swelled with every soldier that fell defending the land. Frustrated and stymied by the seemingly unstoppable enemy, Arthas took increasingly extreme steps to drive them out - he eventually ordered the slaughter of everyone in Stratholme that had been infected by the plague. This most likely included innocent slaughter to prevent Mal'Ganis from adding the citizens to the army of the dead, and strike at Mal'Ganis himself. Arthas failed to trap Mal'Ganis, who escaped to Northrend. Finally Arthas's comrades warned him that he was losing his hold on his humanity.

Arthas' fear and resolve proved to be his ultimate undoing. He tracked the plague's source to Northrend, intending to end its threat forever by killing its supposed leader Mal'Ganis. He stumbled across his long-time friend, Muradin Bronzebeard, brother to the dwarven King Magni, and the dwarf led him to a legendary weapon they hoped would help them combat the Scourge. Instead, Prince Arthas himself fell prey to the Lich King's tremendous power. Believing that it would help him save his people, Arthas took up the cursed runeblade, Frostmourne. Though the sword did grant him great power, the cost was high: Muradin (or so Arthas believed) lay dead, and Arthas began to lose his soul, transformed into the first and greatest of the Lich King's Death Knights. Arthas finally exacted revenge upon Mal'Ganis, removing one of the Lich King's more dangerous jailers and completing the unholy transformation. With his soul cast aside and his sanity shattered, Arthas led the Scourge against his own kingdom — Lordaeron. Arthas started The Scourging of Lordaeron with the murder of his own father, King Terenas Menethil II, and crushed Lordaeron with his newfound unholy strength.

Path of the Damned
With Arthas as his champion, Ner'zhul spread the Plague throughout Lordaeron. What remained of the Order of the Silver Hand struck back, but even mighty Uther fell to the Death Knight's power. On orders from Tichondrius, Arthas took the Scourge north, to the high elven kingdom of Quel'Thalas, to resurrect the Summoner of Archimonde — Kel'Thuzad. The high elves never stood a chance, and their capital, Silvermoon, was ravaged — their millennia-aged Sunwell was warped and used to resurrect Kel'Thuzad as a lich. Thus, both masters were appeased: the Lich King's most loyal worshiper was returned, and the Summoner was unleashed.

Having progressed too far into the Legion's plan (and guarded too closely by Tichondrius) to back out now, Ner'zhul's minions laid siege to Dalaran, reclaiming a spellbook of Medivh, which contained the incantations needed for Kel'Thuzad to summon Archimonde. Before the Summoning, Kel'Thuzad had been reading through the spellbook and noted to Arthas that Medivh's knowledge of demons alone was staggering and that he was far more powerful that anyone had ever realized.

Finally, Archimonde was summoned outside Dalaran, and he immediately gave control of the Scourge to Tichondrius and the Dreadlords. But the Lich King was not done yet. Archimonde may have removed Ner'zhul's control over the undead, but in his eagerness for vengeance against the night elves, he forgot to return the Frozen Throne to Kil'jaeden. Thus, the Lich King remained at large.

During the Legion's invasion of Ashenvale, Illidan Stormrage was released from his barrow prison after ten thousand years of captivity. Realizing Illidan's addiction to magic, and having utilized the Skull of Gul'dan himself years earlier, the Lich King dispatched Arthas to Kalimdor. There, Arthas covertly told Illidan about the powers of the Skull of Gul'dan. Unable to resist such power, Illidan took up the skull and harnessed its vast energies. By doing so, Illidan developed demonic features and vastly magnified power. Illidan, exactly as the Lich King had planned, then proceeded to kill Tichondrius and liberate Felwood.

Without Tichondrius's support team, Archimonde's overconfident ascent of Mount Hyjal led to the unexpected: his annihilation.

Legacy of the Damned
Bristling with power and free to roam the world once more, Illidan set out to find his own place in the great scheme of things. However, Kil'jaeden confronted Illidan and made him an offer he could not refuse. Kil'jaeden was angered by Archimonde's defeat at Mount Hyjal, but he had greater concerns than vengeance. Sensing that his creation, the Lich King, was out of his control, Kil'jaeden ordered Illidan to destroy Ner'zhul and put an end to the undead Scourge once and for all. In exchange, Illidan would receive untold power and a true place amongst the remaining lords of the Burning Legion.

Illidan agreed and immediately set out to destroy the Frozen Throne, the icy crystal cask in which the Lich King's spirit resided. Illidan knew that he would need a mighty artifact to destroy the Frozen Throne. Using the knowledge he had gained from Gul'dan's memories, Illidan decided to seek out the Tomb of Sargeras and claim the Dark Titan's remains. Using his vast, demonic powers, he lured the serpentine naga from their dark undersea lairs. Led by the cunning witch Lady Vashj the naga helped Illidan reach the Broken Isles, where Sargeras' Tomb was rumored to be located.

With the powerful Eye of Sargeras in his possession, Illidan traveled to the former wizard-city of Dalaran. Strengthened by the city's ley energy lines, Illidan used the Eye to cast a destructive spell against the Lich King's citadel of Icecrown in distant Northrend. Illidan's attack shattered the Lich King's defenses and ruptured the very roof of the world. The Lich King had no defense against this spell, and he would have been forever vanquished that day. But at the final moment, Illidan's destructive spell was stopped when his brother Malfurion intervened, sensing that the spell was causing great damage to the world.

Civil War in the Plaguelands
Now that Ner'zhul had openly defied the will of the Legion, he knew that the wrath of Kil'jaeden and his demonic lackeys would be fierce - and at the worst possible time, Ner'zhul was losing his magical power. When he had pushed Frostmourne from the throne, he had caused a crack within the icy cask. Illidan's spell had caused this crack to worsen and now the Lich King's powers were rapidly seeping out like blood from an open wound. Half-way across Azeroth, residing over the unholy remains of his father's kingdom, Arthas was losing power as well — his powers came directly from the Frozen Throne, through his blade Frostmourne, and his hold over the undead was also slipping.

Ner'zhul knew that his time was short. Imprisoned within the Frozen Throne, he suspected (correctly) that Kil'jaeden would send his agents to destroy him. Desperate to save himself, he called his greatest mortal servant to his side: the death knight King Arthas.

Though his powers were drained by the Lich King's weakness, Arthas had been involved in a civil war in Lordaeron. Half of the standing undead forces, led by the banshee Sylvanas Windrunner, had been freed by the Lich King's sudden loss of influence and resented what they had become. Also, another group of undead was still under the control of the Legion's remaining commanders: the three dreadlords Varimathras, Detheroc and Balnazzar. Arthas, called by the Lich King, was forced to leave the Scourge in the hands of his lieutenant, Kel'Thuzad, as the war escalated throughout the Plaguelands.

Ultimately, Sylvanas and her rebel undead (known as the Forsaken) claimed the ruined capital city of Lordaeron as their own. Consuming the old sewers beneath the wrecked Capital City, the Forsaken vowed to defeat the Scourge and drive Kel'Thuzad and his minions from the land. The Lich King was powerless to stop them.

Weakened, but determined to save his master, Arthas reached Northrend only to find Illidan's naga and blood elves waiting for him. He and his nerubian allies (in the form of Crypt Fiends led by the fallen Spider Lord Anub'arak) raced against Illidan's forces to reach the Icecrown Glacier and defend the Frozen Throne.

The Lich King Triumphant
Arthas, with Anub'arak's help, battled his way through their forces until faced with Prince Kael'thas, who challenged him. Kael'thas used the fact that Jaina now hated Arthas to make him hesitate, and fought with his father's reforged runeblade,Felo'melorn (Flamestrike). Flamestrike clashed against Frostmourne but in the end Arthas forced Kael'thas to flee, leaving the path open. He then proceeded to magically activate the four Icecrown obelisks around the glacier, opening the doors to the Frozen Throne.

However, Illidan was waiting for him. An intense battle commenced in which Illidan displayed his newfound demonic powers and nearly defeated Arthas. Until, coming in for the finishing blow, he inadvertently left himself open and Arthas quickly took advantage of it, slicing open the demon hunter's chest. Illidan collapsed, grievously wounded. Arthas then turned towards the open doors of Icecrown, leaving Illidan on the ground instead of finishing him. Rather, before he walked away, Arthas warned Illidan to leave Azeroth and never return.

Arthas entered the hollow glacier and beheld a winding pinnacle chained to the ice. As he strode up the stairs towards his destiny, the voices of those he had forsaken flooded through his mind. First he heard again Uther warning him "If we allow our passions to turn to bloodlust, then we will become as vile as the orcs." Then he heard again more angry remarks from Uther and Muradin, as well as his own responses to them, yet he ignored them, continuing his ascent. Finally, he reached the pinnacle and before him he saw an icy cask, within which was a suit of armour, arranged as if seated on a massive throne. Now only two voices spoke to him: Medivh's previous warning to Jaina and the rasping whisper of Ner’zhul:

"Your young prince will find only death in the cold north."

"Return the blade... complete the circle... release me from this prison!"

With a great cry of strength, Arthas brought the might of Frostmourne to bear against the Lich King's icy prison and with a haunting scream, the Frozen Throne exploded, and shards of the crystal scattered on the ground. With Ner'zhul's thorny helm at his feet, Arthas leaned forward, picked it up and then placed the unimaginably powerful artifact on his head.

"Now," Ner'zhul's voice echoed within his mind and throughout the chamber, "we are one!"

In that moment, Ner'zhul and Arthas' spirits fused into a single mighty being, just as the Lich King had always planned. And thus one of the most powerful entities on Azeroth was born.