Brother Cavil

John Cavil Number One
Battlestar Galactica character
Two copies of the Cavil model
First appearance	"Lay Down Your Burdens: Part I"
Last appearance	Battlestar Galactica: The Plan
Portrayed by
Information
Species	Humanoid Cylon
Gender	Male
Affiliation	Cylons

John Cavil (Number One) is a fictional character and the main antagonist from the re-imagined Battlestar Galactica television series. He is portrayed by . In the fourth-season episode "Six of One", Cavil's model number was revealed as Number One.

John Cavil, aka Number One, is a humanoid Cylon model that appears as a highly rational, eccentric man in his late-sixties. The Cavils have a heavy sarcastic demeanor and a sense of humor. They take neither religion nor death seriously and are the only atheist Cylon model. A Cavil is first seen aboard the Galactica assuming the role of a priest, offering spiritual guidance, and going by the name "Brother Cavil".

One of the unique characteristics of the Cavils is the sadistic, cruel and Machiavellian streak in their personalities. The Cavils openly mock their fellow Cylons every time they attempt contact with humans, even when it is absolutely necessary.

Even though they view death as only a nuisance, the Cavils are extremely displeased with pain (placing the blame on the Final Five). This view fuels the idea that the Cavils wanted death to the humans to be as quick as possible, but were unprepared for the aftermath. Their attitude towards mankind's mortality, rather than irrational hatred, derives from their overall lack of knowledge about absolute death and the consequences that it carries. As revealed on Battlestar Galactica: The Plan, the Cavil that was stationed in Caprica learns from Samuel Anders the motives for the resistance; that humans do not leave anyone behind, even their dead. Respecting their resilience, the Caprica Cavil agrees with Caprica Six and Sharon Valerii (Boomer) to abandon the Colonies. Disappointed with the other Cylon models after failing to accomplish anything through boycott and sabotage, the Galactica Cavil fails to learn any lesson. As they are discovered and airlocked from Galactica, Galactica Cavil swears to "box" Caprica Cavil for his insubordination and is indicated to be the same Cavil that is the main enemy of season four given his plans to destroy humanity once and for all once he resurrects.