The Cylons are entirely comprised of robots, originally the creation of a reptilian race that were also known as Cylons. From that seed, the Cylon Empire became a dominant, aggressive force that spread throughout the galaxy. Arresting this spread were the humans of Twelve Colonies of Man, who fought a Thousand-Yahren War where the humans were destroyed by their own hubris and the machinations of traitors, such as Baltar and Zee.
In an alternate reality, Adama presided over the war effort as president of the Quorum of Twelve. Following Cylon victory, Adama relegated his role as the leader of the Colonial Resistance, leading to the appointment of Baltar to oversee humanity's total subjugation or destruction, whichever suits the needs of the moment (Classic Battlestar Galactica Vol. 2 #3).
Exploiting Zee's talents and drive to find ways to selfishly prolong his own existence, Baltar becomes the the first hybridized Human-Cylon entity, known by his amalgamated name Baltifer (Classic Battlestar Galactica Vol. 2 #2 & #3).
There are two known Cylon spacecraft:
- Basestar (or Baseship): Capital ships of the Cylon military force, analogous to the Colonial battlestar. Baltar commands such a craft.
- Raider: The primary fighter of the Cylon forces, manned by two pilots and a ship commander. Raiders have been outfitted with electronic tractor beams, capable of ensnaring craft (Classic Battlestar Galactica Vol. 2 #2).
- Centurion, a foot soldier of the Empire in humanoid form, often armed with laser rifles.
- Centurions are also outfitted with an electric stunning weapon in their vambrace, used on Starbuck during his time in custody aboard Baltifer's basestar (Classic Battlestar Galactica Vol. 2 #3).
- A Centurion is modified to convey a decrepit Doctor Zee, complete with necessary life sustaining equipment that Zee requires.
- Cylon Warden, a large unit armed with rotating weaponry, and center piece of Doctor Zee's holding cells.
- Tech spider, a large crawlon-like robot used to repair, analyze, scan, and dissect technological items.
Utilizing a captured Imperious Leader and other Cylon units, Starbuck's technicians and scientists create two distinct anti-Cylon technologies.
The sensor shield is a defensive technology circumventing Cylon electronic detection abilities, employed on the incongruous Galactica.
Its use requires the ship to be immobile, presumably to avoid any spatial disruption (Classic Battlestar Galactica Vol. 2 #4).
It has the drawback of also affecting Colonial systems, and thus it is deployed when units are clear from the disruptor's sphere of influence (Classic Battlestar Galactica Vol. 2 #3).