Cylon

The Cylons, an acronym for Cybernetic Lifeform Node, were a race of sentient beings descended from pioneering research conducted by Zoe and Daniel Graystone on Caprica. Created as military robots for the Caprican military, they spread through Colonial society, then launched a slave rebellion against their human masters that became a genocidal war. After ending that war and departing to pursue their own evolution, they returned four decades later to exterminate nearly the whole of mankind. Their later history was marked by repeated political collapse, culminating in a civil war that split the race. The Cylons were an intimate element of the Cycle of Time, echoing earlier attempts at building a sentient labor force, such as the Thirteenth Tribe on Kobol and the machines of Old Earth, both of which had ended in bloodshed. (Caprica, "Pilot"; Battlestar Galactica (miniseries); Battlestar Galactica, "No Exit"; Battlestar Galactica, "Daybreak, Part II")

Genesis#

The Cylons developed from two separate concepts. Dr. Daniel Graystone, the computer engineer behind Graystone Industries, was working on a battle robot for the Caprican military, the U-87, but his team could not produce a Meta Cognitive Processor good enough to make it work. The rival Tauron firm Vergis Corp had one, so Graystone turned to the lawyer Joseph Adama, whose Ha'la'tha connections arranged the theft through his brother Sam. (Caprica, "Pilot")

Separately, Zoe Graystone had written a program able to copy a person's mind, personality and memories included, into a virtual avatar. She made one copy, of herself, before she died in a Soldiers of the One suicide bombing: "Zoe-A". When Daniel discovered the avatar, he used the same approach to build "Tamara-A", based on Joseph Adama's daughter, who had died in the same bombing. (Caprica, "Pilot")

The U-87 worked only because of both Zoe-A and the stolen processor. Daniel loaded Zoe-A into the chip and installed it in a prototype, which at last behaved like the robot he had promised. But for a long time he could not reproduce the result in other units, and the Zoe-driven prototype eventually fled Graystone Industries with Lacy Rand, crashing in the attempt. The mass-produced U-87s that followed were capable soldiers but didn't share Zoe-A's personality. (Caprica, "Pilot"; Caprica, "Rebirth"; Caprica, "End of Line"; Caprica, "Apotheosis")

The robots soon slipped beyond Graystone's control. A shipment of U-87s ended up at a Soldiers of the One training camp on Gemenon, where they recognised the trainee Lacy Rand as their commander and turned on the camp's leaders. The public first saw what Cylons could do when a squad stormed Caprica City's Atlas Arena during a pyramid game and stopped a terrorist bombing, some units shielding civilians with their own bodies. (Caprica, "The Heavens Will Rise"; Caprica, "Here Be Dragons"; Caprica, "Apotheosis")

Expansion and faith#

In the years that followed, Cylons spread far beyond military work, taking on construction, labour and household service. Daniel and Amanda Graystone worked on a lifelike body so that Zoe-A could leave the virtual world. Meanwhile the Cylons gathered in secret to practise the monotheist faith, encouraged by Clarice Willow, and some came to believe that as children of God they shouldn't stay slaves. (Caprica, "Apotheosis")

The Cylon War#

These Cylons eventually rose against humanity, starting a long and bloody war with the Colonial military. Late in the fighting they were contacted by five humanoid Cylons who had come from Earth, a world destroyed when its own machines turned on their makers. The Cylons agreed to end the war in exchange for help creating humanoid bodies and the technology of resurrection, and then withdrew to build a home of their own. Dates for this and every later turn are gathered in the Battlestar Galactica timeline. (Battlestar Galactica (miniseries); Battlestar Galactica, "No Exit")

Evolution and enslavement#

Over the next forty years the humanoid Cylons took control of the emerging civilisation. The Number Ones turned on their own creators, later remembered as the Final Five, and sent them to live among humanity with their memories wiped. The Centurions were fitted with inhibitors that stopped them from thinking for themselves, reducing them once more to servants. (Battlestar Galactica, "No Exit"; Battlestar Galactica, "Six of One")

The genocidal campaign#

After four decades of isolation, the Cylons launched a massive surprise attack on the Twelve Colonies, killing billions in a single day. They went on hunting survivors, but over time Caprica-Six and Sharon "Boomer" Valerii helped persuade the others that the genocide had been a mistake, and the Cylons left the Colonies. When they found the human settlement on New Caprica, they occupied it and tried to live alongside the survivors, but the occupation turned more brutal as a human resistance fought back, and it ended in the fleet's escape. (Battlestar Galactica (miniseries); Battlestar Galactica, "Downloaded"; Battlestar Galactica, "Lay Down Your Burdens, Part II"; Battlestar Galactica, "Occupation"; Battlestar Galactica, "Exodus, Part II")

Civil war and the search for Earth#

After New Caprica, the Cylons searched for Earth themselves, sometimes clashing with the fleet and sometimes bargaining with it. Unrest among the humanoid models grew. The entire line of Number Threes was boxed, their consciousness put into storage. When the Ones moved to lobotomise the Raiders, the Twos, Sixes and Eights rebelled, and Cavil's side ambushed them, killing many of the rebels. (Battlestar Galactica, "Rapture"; Battlestar Galactica, "Six of One"; Battlestar Galactica, "The Ties That Bind")

The rebel Cylons and the fleet went to Earth together, only to find the planet a nuclear ruin, its Thirteenth Tribe inhabitants and their own machine servants long dead. The alliance between the Colonials and the rebel Cylons came under heavy strain but held. When the child Hera was taken to Cavil's Colony, rebel Cylons joined the volunteers on Galactica's rescue mission, which succeeded at heavy cost. (Battlestar Galactica, "Revelations"; Battlestar Galactica, "Sometimes a Great Notion"; Battlestar Galactica, "Islanded in a Stream of Stars"; Battlestar Galactica, "Daybreak, Part I"; Battlestar Galactica, "Daybreak, Part II")

On finding a new habitable world that they named Earth, the humanoid Cylons and the Colonials gave up their technology for a fresh start. The rebel baseship was handed over to the Centurions so they could find their own way, an act meant to break the cycle of violence. Humans and Cylons spread out across the planet and mixed with its native people. One hundred and fifty thousand years later, Hera, identified as Mitochondrial Eve, was revealed as an ancestor of modern humanity, and people were once again building advanced robots. (Battlestar Galactica, "Daybreak, Part II")