Flayer

To those who have turned their faces away, to those who are faithless and wretched in their jealousies. To those who have denied us. To those who have denied me. I will wreak vengeance. I will wrench your souls and break your bones. I will cast hunger through your cursed existence. Down the eons you will not forget. I will grant you this gift from love turned aside and make you like me, break you in my image as you have broken me. I shall cast the fear of myself into you and all of your kind. I am Llandu'gor. I am the hunger, I am the flayer and from this moment you shall be too.

-- Devourer (Novel); pg 99

LLandu'gor, called the Flayer, was one of the mighty C'tan. Star gods who ruled over the Necrontyr and helped with the biotransference that made them into Necrons. In the last days of the War in Heaven, the Necron forces turned on their C'tan masters. Most were shattered, rent into shards which were separated and individually imprisoned. However, it is said that of the C'tan only Llandu'gor was utterly destroyed. Rumored to have met annihilation at the hands of the Maynarkh Dynasty, on the order of the Silent King, the Flayer's last act was to curse the Necron race. This curse, one of the varieties of creeping madness which plague the waking Necrons, is referred to as the Flayer Virus, and is the cause of Necrons becoming Flayed Ones.