The Necrontyr were an ancient and long-extinct race of humanoids.
The Necrontyr's planet of origin was barren and radiation-blasted, making it incredibly hostile to life. Their bodies were ridden with radiation sickness and they lived a morbid life, constantly fearful of their coming deaths. Their cities were built in anticipation of their demise, little more than vast tomb complexes with a few temporary homes for the living.
The Necrontyr attempted to overcome their mortality with scientific means, but realized after thousands of years that their bodies could not be changed to survive on the planet. Instead, they developed spacefaring technology, though of a much slower and more uncertain nature than the Old Ones'. Where the Old Ones were able to move between the stars in seconds, the Necrontyr had to use slow-moving ships, equipped with stasis crypts, to reach out to the stars. They clad their ships in living metal to withstand the rigors of space flight.
The Meeting of the Races
After much time, they met the Old Ones. This meeting of a short-lived, dour race with a hopeful, nigh-immortal one set a fire of rage burning in the hearts of the Necrontyr. From this moment on, they turned their entire lives to destroying the Old Ones.
When war was declared, the Necrontyr realised they would never be able to win. They were constantly outmanoeuvred by the Old Ones' mastery of the Webway. Eventually they were pushed back to being merely an annoyance in the outer regions among the Halo Stars. The fury of the Necrontyr was cooled after many thousands of years of imprisonment, and their disgust of the Old Ones turned into an utter hatred of all life.
The Star Gods
As their star had haunted their own existence, the Necrontyr studied the stars in an attempt to understand more of how they worked and to try to find something they could unleash on the Old Ones. Eventually, they found something so ancient as to predate even the Old Ones. This sentience fed on the stars they orbited but had little conception of the universe around them other than satisfying their need for energy. This was the weapon they needed to fight the Old Ones. Their etheric form made them invincible to conventional weapons. They were named C'tan, or Star Gods.
How the Necrontyr managed to communicate with these beings is unknown, but the Necrontyr knew these beings could not understand the material universe without a physical, material body. So they made bodies for these creatures out of their living metal, allowing these bodies to expand and change at will. Supposedly, "translucent streams of force" were seen as the first being moved across the incorporeal starlight bridge into the body forged for it.
The first being to come across the starlight bridge was Aza'gorod, the Night Bringer. As the creature became more manifest and intelligent, the Necrontyr began to worship the C'tan as gods for their supreme powers. The C'tan turned the Necrontyr into slaves and enjoyed ruling over them with cruelty and distrust.
The Necrons Rise
Soon the Necrontyr were ready to begin the battle anew with the Old Ones. The C'tan then made a proposition to the Necrontyr that they could not refuse: immortality for their race. Their cursed flesh would be discarded in favour of bodies like their gods', made of living metal. Their bodies would be consumed and their minds transferred into the new metal bodies with which they could continue the war with the Old Ones. Whether the Necrontyr knew the consequences of this is unknown, but their entire race was purged when it was transferred into the metal bodies. Their minds were dulled and they were drawn into eternal servitude. Only a few of the Necrontyr retained any form of independent thought, but it was much reduced. The Necrontyr were no more, and the Necrons were born.
A Dead Race