Everything you were afraid to ask about "Battlestar Galactica"

CHARACTERS: CYLONS

There are 12 humanoid Cylon models that fit into two categories: conventional Cylons and the "Final Five." Conventional Cylons exist in multiple copies. Over the course of the series, some of these Cylons have taken on distinct personalities. The Final Five, meanwhile, are a mysterious group whose identity has been kept secret from the other Cylons -- and may or may not exist in multiples. At the moment, only four of them have been revealed.

Conventional Cylons

Number Three (Lucy Lawless):

Originally introduced as D'Anna Biers, a documentary filmmaker, this Cylon is narcissistic and obsessive. Over the course of the third season, she comes to play an increasingly prominent role, becoming obsessed with the identity of the Final Five Cylons. She has visions of the Final Five during the downloading process, which leads her to repeatedly commit suicide and download into new bodies. In the Temple of Jupiter, on the Algae Planet, she sees the faces of the Final Five, after which she is "boxed," or disabled. She is resurrected near the end of the fourth season.

Number Five (Matthew Bennett):

This model first appears as Aaron Doral, a P.R. man, in the "Galactica" miniseries. He makes some sporadic appearances in the ensuing seasons but remains a marginal Cylon character. He sides with the Brother Cavils and Simons in the Cylon civil war.

Baltar's Hallucination (Tricia Helfer):

A hallucination of Caprica Six that exists only in Baltar's mind, she appears sporadically to give him advice. This version of Number Six is pious and sexually aggressive. She is fond of telling Baltar that he is the Chosen One, and she may or may not be caused by a chip implanted in Baltar's brain.

Caprica Six (Tricia Helfer):

This Cylon seduces Gaius Baltar and plays a key role in the Cylon attack on the Twelve Colonies. Following the attacks, she becomes a Cylon hero and has hallucinatory visions of Baltar. She comes to question the decision to attack the humans and advocates a more cooperative approach, eventually helping Sharon Agathon return Hera to the Galactica. After that, she is held prisoner in the brig on Galactica, where she begins having sex with Tigh -- and is currently pregnant with his baby.

Sharon "Boomer" Valerii (Number Eight) (Grace Park):

A sleeper Cylon who was part of the Galactica's crew before the Cylon attack, Valerii gradually realizes that she is a Cylon in the first season. At the end of that season, she shoots Cmdr. Adama. Like Caprica Six, she has trouble coming to terms with the Cylon destruction of the Colonies and becomes an outspoken advocate for coexistence with humans. She then changes her mind about human cooperation and, unlike other Number Eights, sides with the Brother Cavils, Number Fives and Simons in the Cylon civil war.

Sharon "Athena" Agathon (Number Eight) (Grace Park):

This Cylon falls in love with Karl "Helo" Agathon during a mission on the planet Caprica. She helps him and Starbuck return to the Galactica. Once there, she is imprisoned and distrusted, but eventually becomes a valuable part of the ship's crew. She gives birth to Hera, a human-Cylon hybrid child, but is told that it died. She discovers that her child is alive and rescues it from the Cylons. In the fourth season, she is placed in the brig on Galactica after she shoots another cooperative Cylon.

Brother Cavil (Dean Stockwell):

A cynical, snarky and atheistic Cylon model, Cavil first appears as a priest on board the Galactica. He sides with the Number Fives and Simons during the Cylon civil war.

Leoben Conoy (Callum Keith Rennie):

A wily and dishonest Cylon model, Leoben has an obsessive relationship with Starbuck. During the occupation on New Caprica, he imprisons her in an apartment-like cell, and tries to persuade her to love him. It doesn't really work. He sides with the Number Eights and Sixes in the Cylon civil war.

Simon (Rick Worthy):

Simon is a bald Cylon model who makes rare appearances on the show. He first shows up in the Cylon fertility farm on Caprica, posing as a doctor. He sides with Brother Cavil and the Number Fives in the Cylon civil war.

The Final Five

Chief Galen Tyrol (Aaron Douglas):

The deck chief on the Galactica, Tyrol is in charge of the ship's hangar deck and ship maintenance. At the beginning of the series, he is engaged in a secret affair with Sharon Valerii and is rather perturbed when she turns out to be a Cylon. On New Caprica, he marries Cally -- the crew member who shot and killed Valerii -- has a son named Nicholas, and becomes a key member of the insurgency. His discovery, in the third-season finale, that he is a Cylon is presaged by his somewhat random discovery of the Temple of Five on the Algae Planet. It is worth nothing that both of Tyrol's parents were clergy -- suggesting that the Final Five Cylon models may have religious significance. He becomes somewhat unhinged during the fourth season, after he discovers that he is a Cylon -- and after Tory flushes his wife out of an airlock.

Col. Saul Tigh (Michael Hogan):

Tigh is the Galactica's embittered and alcoholic executive officer. He is a bumbling figure with a strong hatred of the Cylons. Before arriving on the ship, he fought in the First Cylon War and met Adama while working in the commercial fleet. With Adama's help, he was reinstated in the military. During the settlement of New Caprica, he was a leading member in the insurgency, losing his eye during a period of incarceration. In the third season, he poisons his wife after learning that she has given secret plans to the Cylons. Then, just when things seem to be getting better, he finds out that he is a Cylon. During the fourth season, he begins a sexual relationship with Caprica Six, who is being held captive on the Galatica. She eventually becomes pregnant with his child.

Tory Foster (Rekha Sharma):

Foster is President Roslin's aide -- a supporting character that first appeared after Roslin's previous aide, Billy, was killed in a bar shootout. We eventually discover that she's a Cylon. In the fourth season, she has a sexual relationship with Baltar, kills Cally, and sides with Number Three during the tense human-Cylon hostage situation.

Samuel Anders (Michael Trucco):

Anders is Starbuck's loving but alienated husband. Before the Cylon attack, Anders was a member of a sports team doing high-altitude training. Afterward, he becomes a member of the human resistance and, eventually, Starbuck's lover. She returns to Caprica to rescue him and bring him on board the Galactica. After the two are married, they grow apart, and he has trouble coming to terms with her death. In the third season, he begins a sexual relationship with Tory Foster and learns that he is a Cylon. He begins acting strange when Starbuck returns from the dead.

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