C'tan

The C'tan or Necron Star Gods (in the Eldar tongue they are called the Yngir) are said to be the oldest intelligent beings in existence in the Milky Way Galaxy. It is said that they were created at the very beginning of the universe, spawned from swirling gases and enormous amounts of energy, and as such are etheric creatures by nature. In their natural form they are vast beings and spread themselves over the surface of a star, absorbing its solar energy to feed themselves. After a time, they learned to use diaphanous wings to travel to other stars to continue their consumption when their host star died. The matter around them was so insignificant that it did not register on their voracious appetite. They are able to interact with the physical world thanks to the technology of the Necrontyr which transferred their consciousnesses into robotic bodies made of the living metal called necrodermis. The C'tan used the hatred of the Necrontyr towards the ancient species called the Old Ones to help them gather the more appetizing energy of living beings that they craved. The C'tan hate the Warp and its psychic energies (even as they crave the living energies of organic beings) and have thus had the Necrons construct a series of 'pylons' on the world of Cadia, which, when completed, will close off the Warp from the material universe entirely, utterly destroying any living creatures with a soul, leaving all other life in the galaxy as nourishment for the C'tan.



The Ancient Times
Millions of years ago, the ancient intelligent race known as the Necrontyr discovered an sentient being composed entirely of energy feeding from their home star system's sun when their technology had advanced far enough for them to detect its presence. The Necrontyr managed to communicate with this being, and eventually built the robotic bodies they now inhabit. They are made of the same material as the Necrons' starships and bodies, an alloy of "living metal" called necrodermis. The early Necrontyr named these entities the C'tan, which in the native Necrontyr langauge means "star gods," or "star vampires." The C'tan's essences were transferred, according to the Eldar, across an "incorporeal starlight bridge" into their new necrodermis bodies, so that the energy beings whose essences had once stretched for thousands of miles were now compressed into much smaller, physically tangible bodies. The C'tan made use of the Necrontyr's burning hatred of the Old Ones to wage war across the galaxy and collect living beings to consume their life forces, which the C'tan enjoyed far more than their previous bland diet of solar energy. They also found a love of worship, or more accurately, of others worshipping them. They were revered by the Necrontyr as gods and eventually the C'tan forced that race into complete slavery. The C'tan eventually tricked or convinced the Necrontyr into leaving their organic bodies and transferring their consciousnesses into shells of living metal made of necrodermis, becoming the Necrons. In the ancient, primordial conflict known as the War in Heaven between the C'tan and their slaves the Necrons against the Old Ones and their allied younger races like the Eldar and the Krork, their harvests of living creatures started to run dry. Then the Eldar Laughing God tricked the C'tan into consuming each other until only four remained in the Milky Way Galaxy. Not long after that, a plague of Enslavers emerged from the Warp, drawn by the conflict, which apart from destroying the remainder of the Old Ones in the galaxy, also depleted the Necron's so-called "red harvests" of living beings further. Thus the C'tan and the Necrons decided to enter stasis on various "tomb-worlds" until life had repopulated most of the galaxy and their harvests could begin again.

Recent History
After millennia spent in their stasis tombs on the Necron Tomb Worlds, the four remaining C'tan in the galaxy include:
 * The Nightbringer has impressed its image as that of the grim reaper itself on the psyche of the younger races, apart from the Orks (since they do not fear death). Upon entering stasis it was almost destroyed and starved but was released accidentally by the Space Marines in the 41st Millennium, which caused the Necrons to begin to awaken from their ancient sleep.
 * The Deceiver came out of stasis an unknown time ago and has been weaving plots ever since, including the destruction of the Eldar weapon Talismans of Vaul which were designed to destroy the C'tan on their emergence.
 * The Void Dragon, the most powerful C'tan, resides in stasis, theorized to be located beneath Mars and is rumoured to be the Machine God venerated by the Machine Cult of the Adeptus Mechanicus.
 * The Outsider became insane due to its consumption of other C'tan, a trick played on it by the Eldar Laughing God. It is currently imprisoned in a Dyson Sphere beneath the galactic plane. The Eldar Harlequins (Followers of the Laughing God) whisper that "one dark night, it shall return."

Other instances of the C'tan
The Imperial Inquisition employs elite Officio Assassinorum Assasins, one of which, the members of the Callidus Temple, use a weapon called a C'tan Phase Sword. It is unknown what specific relation the weapon has with the C'tan themselves. The most likely explanation would be that the C'tan Phase Sword is made out of necrodermis, as explained in the Necron codex where a Callidus assasin attacks an Imperial planetary governor, only to have her C'tan phase weapon absorbed into the "governor" and become a part of his body. This governor was most likely the C'tan called the Deceiver in another of its myriad disguises.

The primary weakness of the C'tan is their inability to comprehend the Warp. It is speculated that they find it impossible to survive in it and are particularly susceptible to warp spawned magics and psykers. They had a plan to block off the warp forever in an attempt to remove their single greatest threat. It is also speculated that they have set up a series of 'pylons' on Cadia, possibly for this purpose. Whether these pylons have anything to do with the Eye of Terror is unknown, but it is unlikely, as the Eye was not opened until after the C'tan were in their stasis tombs. There is also a Necron object on Armageddon in the central region of the planet.