Through demonic punishment, the Lich King was born with a singular objective: controlling the massive throng of undead known as the Scourge.
Ner'zhul was an elder orc shaman who rose as high as warchief of the orc clans of Draenor... and fell low enough to become a slave of the Burning Legion. After the Second War drew to a close, Ner'zhul--guided by visions of death--frantically opened new portals to worlds that the orcish hordes might invade, but the magical stress of creating so many portals at once tore Draenor apart. Ner'zhul escaped the death of his homeworld by fleeing into the nearest rift, only to find the demon Kil'jaeden lying in wait for him. Kil'jaeden had long manipulated Ner'zhul's visions to guide the orcs down a dark path, and now the demon punished his puppet by destroying Ner'zhul's body and encasing his spirit in an icy cask that would come to be called the Frozen Throne. This act birthed the Lich King, a spectral presence made to command the Scourge, an army of undead that would serve as the Burning Legion's advance weapon against Azeroth.
Despite his orders, the Lich King plotted to break free of the Legion's influence. During the Third War, he summoned Arthas Menethil, the fallen prince of Lordaeron, to serve as his most loyal death knight. When the Lich King was threatened by the forces of Illidan the Betrayer, Arthas traveled to the Frozen Throne of Northrend and broke the ice surrounding his master, donning the Lich King's helm and merging with him. Years later, the Alliance and Horde would march to destroy the Lich King, but they discovered that the Scourge, now loosed upon Azeroth, would always need a leader. The brave highlord Bolvar Fordragon volunteered to become the new jailor of the damned, dedicating his existence to containing the ravages of the undead.