Karthus is a terrible creature who was once a mortal so obsessed with death that he eagerly embraced the gift of undeath. Now in his unlife as a lich, Karthus is closer to his beloved grave than he ever imagined. He commands magic with oblivion as its source, and seeks to bring his grim truth to the rest of the world: only in death does life gain clarity and purpose.

Even as a boy, Karthus was different. There was a darkness within him that could not be denied. The young child clung to the shadows and shunned the company of others. He snuck into the funerals of strangers, and spoke to their tombstones in the cemetery. He sought out corpses of animals to preserve and memorialize them, creating a grim collection of morbid art. Karthus volunteered to tend to the sick and dying, though his intentions were not to help, but to closely witness the passing of those who were beyond help. Ultimately, he went so far as to elaborately stage his death, and he secretly observed his own funeral with intense fascination. When others discovered what Karthus had done, they were so shocked and disturbed that, in a way, he became truly dead to them. Karthus found himself fully rejected by the living.

His isolation only served to fuel his obsession. Karthus delved further into his exploration of death, and became fascinated by the legends of the Shadow Isles. There, it was said, the specters of the deceased continued on in unlife everlasting. Possessed by these tales, he knew he had to discover for himself if they were true. Journeying to those dreaded isles, Karthus soon found himself wandering through the mist, overcome by the surreal beauty of the place. He felt as if he had finally come home. He had always chased the elusive purity of the moment of death, when life passed and in a single instant achieved meaning. Karthus saw that undeath was like that moment, preserved in dread stillness forever. He had discovered his destiny, to cross over the veil and leave the living behind for eternity. Something awoke in the Shadow Isles that day, when Karthus did something no other creature had ever done: he willingly gave his life over to undeath. When he reentered the world, Karthus had become the embodiment of his own obsession. An undying lich with the keys to life and death, he seeks to bring his dark requiem to the world.

『There is no sweeter song than the last breath of the dying.』 -- Karthus