Basestar (TRS)
In the re-imagined series, Cylon Basestars (also referred to as "baseships" or "Cylon battlestars") are by far the most prominent example of Cylon presence in the known universe. They easily dwarf a colonial battlestar and appear to be technologically superior in every way, including being able to release wings of hundreds of Cylon Raiders at the same time (according to the number of launch "slots" on the Basestar, it can release 792 Raiders as seen here, here, and here).
Beyond this, not much is known. Basestar operations would suggest that they have large crew complements, although there is ample evidence to suggest their operations are largely automated. Indeed, the large complement of raiders would suggest on-board manufacturing facilities (The BSG Bible).
Its weapons complement indicates missiles on a similar principle to the United States' VLS system, which is capable of launching coventional or nuclear missiles.
Soon after the planet Kobol was discovered by the Galactica, a Basestar Jumped into orbit, resulting in the destrucion of 2 Raptors. Subsequently, Commander Adama devised a plan to destroy the Basestar by using a Raptor fitted with a Cylon transponder to sneak a nuclear warhead inside it. Pilot Lt. Sharon "Boomer" Valerii, a Cylon sleeper agent, flew a Raptor along with ECO Lt. Margaret "Racetrack" Edmonson to infiltrate the inside of the Cylon Basestar. While inside, they saw that basestars have a vast, cavernous interior made of bio-mechanical components, without a distinct floor or ceiling. The walls appear fleshy and alive, similar to the synthetic organs filling the interior of a Raider.
Boomer and Racetrack successfully detonated the nuclear warhead, completely destroying the Basestar. This was perhaps the first time since the Cylon Attack's beginning that Colonial forces successfully destroyed a Cylon Basestar.
Shortly thereafter, Valerii's cylon programming activated, causing her to attempt the assasination of Commander Adama ("Kobol's Last Gleaming, Part II"). She was subsequently killed by Specialist Cally. Consequently, Edmondon is now the only living member of the Galactica's crew that has ever seen the inside of a Basestar ("Resistance").