In the TV show, the Cylon hierarchy was pretty straightforward. At the top is the Imperious Leader, followed by the IL-Series robots. The gold-coloured Cylon Commanders like Vulpa are often in charge of individual baseships or bases, with Centurions forming the backbone of the Alliance forces. On Gomoray and other capitals are Cylon civilians, who may take up arms if required. One further model involves the humanoid Cylon, which resembles a human in appearance but is a cybernetic entity just like the IL-Series. Looking at the unfilmed scripts, I Have Seen Earth mentions Cylon mining drones, which suggests that such machines can be adapted to specialised roles. Baltar is escorted by Centurions clad in black armour in The Beta Pirates, who are the elite forces serving the Imperious Leader.
In the novels, which are closer to the original concepts for BSG, things are more complicated because the Cylons are reptilian cyborgs. There is still a hierarchy similar to the aired show, but the nature of each level of Cylon society differs in a number of respects. Starting with the Imperious Leader, a Cylon only achieves this position after receiving three brain transplants. These allow him access to a greater level of cognitive ability, as well as the sum of Cylon knowledge. In Saga Of A Star World, the Cylon ruler can also communicate with the AI of each previous leader.
The main IL-Series Cylon in the books is Lucifer, a cybernetic entity who is not as hostile towards the humans as other Cylons. He is far more autonomous, able to replicate the thought processes of a second and third Cylon brain. In fact, he looks down on these higher levels of Cylon thinking. As with his counterpart, Spectre, he is capable of devious strategies to ensure his own survival. In Surrender The Galactica, he adopts the disguise of a Borellian Noman, echoing the humanoid Cylon in Galactica 1980.
Spectre is part of an older range of machines, the IL-2 Series. In Surrender The Galactica, he notes that his line was originally designed as an honour guard for the Imperious Leader. Despite being assigned to a remote base on Antila, Spectre is able to accumulate large amounts of resources. He needs these to keep his own garrison going, due to the loss of equipment and soldiers to the local human resistance. Later, he is able to escape from the planet and gain a post on the staff of the Imperious Leader. Despite being similar machines, there is an intense rivalry between Spectre and Lucifer which borders on hatred. Other IL-Series robots occupy Cylon colonies such as Gomoray.
Cylons who receive a second brain usually serve as Commanders. This implant enhances cognitive ability and allows the individual to meditate. Unlike the TV show, Cylon Commanders have silver armour and their rank is determined by black bands on either their shoulders or, with a higher award, the waist. These officers are identified in The Cylon Death Machine as Warriors of the Elite Class, perhaps analogous to the black-clad Centurions in The Beta Pirates. Unlike the IL-Series, these Cylons rarely show any kind of ambition. However, once in a while, there is a rogue individual like Vulpa who does so. Not only that, but Vulpa openly questions the validity of pursuing the humans. This leads his exile on Tairac.
Cylons with first-brain status serve as Centurions and pilots, but they have very basic intelligence. However, the Imperious Leader thinks that even these Cylons are capable of out thinking a human. These Cylons have cybernetic enhancements such as their visors and armour.
The biological Cylons still exist, but lacks any cybernetics. Instead, they receive the first genetically-engineered brain implant. Such an individual is designated a citizen in The Living Legend, suggesting a civilian role. Are these creatures the closest surviving descendants of the original reptilian Cylons?
Cylons drones exist at the bottom of Cylon civilisation. They lack any brain implants or cybernetics. According The Living Legend, “Cylon drones, whose achievements or, rather, lack of them qualified them for nothing more than the rudimentary brains that had trained and educated them in their early years, performed only the basest tasks in Cylon society.” Drones may have helped to rebuild Gomoray after the destruction of the Delphian Empire.
Cybernauts are similar to the robotic Centurions seen in the TV show, used to boost the Cylon forces. Even so, these machines have proved to be very complex and Doctor Wilker has problems figuring out how they work in Experiment In Terra. In The Young Lords, Spectre has designed his own version, although they prove to be more devious than him in the end. The ghost ships in The Cylon Death Machine might be considered an extension of the Cybernaut idea.
So the Cylons in the Berkley novels are quite different from those in the TV show. They even have individual characteristics, as seen in the likes of Vulpa. When interrogating Cree, this Cylon even speaks to the prisoner in the Cylon equivalent of a whisper. In the first novel, a Cylon Centurion laughs at one point, something impossible for the Cylons of the TV series. Even the Imperious Leader “blended a burst of laughter into the sarcasm of his voice-box mixture.” This wider range of expressions echoes a rather sinister aspect from the unused Crossfire script, where a Cylon officer actually smirks. For information about the Cylons, see the first two novels and The Living Legend, which seem to include ideas closer to the original show. Richard Hatch’s novels also continue with the concept of the Cylon cyborg, but in a very different direction.
Note: I’ve used the spelling and names from the novels.