However much we may look to Inarius as the reason that Sanctuary exists, without Lilith there would be no Sanctuary and no Nephalem.
Before the coming of the Nephalem, Imperius was the unquestioned greatest warrior in all creation.
It's not a demon, it's not an angel, it's definitely not a Nephalem. What is Trag'Oul, and how did it come into existence?
From this whirling nightmare, this bloated ruin of the first evil's corpse crawled the demons. The Burning Hells could in a real sense be said to be the blackened corpse of Tathemet itself, and at the center of the Hells lies the Black Abyss, from which rose the Great Evils. Essentially birthed from the seven heads of Tathemet, there were the three Primes -- Mephisto, Baal and Diablo -- and the four Lessers.
Because I promised you some Diablo Know Your Lores, today we're looking at the origins of the world of Sanctuary, the mortal realm that has seen the machinations of the Prime Evils as well as near-extinction at the hands of Malthael, the former Archangel of Wisdom and current Angel of Death.