|Portrayed by||Tricia Helfer|
The first model explicitly revealed to be a Cylon in the mini-series, the Sixes often use seduction to their advantage. Important copies include Shelly Godfrey, Gina Inviere, Head Six, Caprica-Six, and Natalie.
One of the models, later known as Caprica Six, on her way to meet with Dr. Gaius Baltar, murdered an infant by breaking its neck. This could either be considered sociopathic, or a mercy killing due to the coming Cylon attack. She went on to save Baltar's life when his house was struck by a blast wave from the Cylon attack on Caprica.
Caprica Six has a love-hate relationship with Gaius Baltar, alternately defending him to other Cylon models or leaving him to suffer at their hands and progressing to reinitiating a sexual relationship with him.
Shelly Godfrey appeared in season 1's episode Six Degrees of Separation. She was a Number Six who was in Galactica after the Cylon attack. She accused Baltar of treason, by sabotaging human defenses, and therefore, being guilty of killing several millions of humans in that attack. She also appears in Battlestar Galactica: The Plan TV movie, which details a bit more her presence (and fate) aboard Galactica.Number Six (Caprica-Six / Shelly Godfrey / Gina Inviere / Natalie Faust / Lida / Sonja)
Another Number Six, Gina, acted as a contractor for the Battlestar Pegasus and was in a relationship with Admiral Helena Cain. When Cain discovered that Gina was a Cylon agent, she ordered her crew to "push her programming" in an attempt to see if Gina was vulnerable to emotional trauma. Gina later escaped with Baltar's aid, assassinated Cain, and founded a resistance group in the fleet, preaching peace with the Cylons. While it seemed that Gina may have developed feelings for Baltar and was going to pursue a relationship with him, she detonated a nuclear warhead (provided by Baltar) which destroyed Cloud Nine, some other fleet ships, and generated an electromagnetic signature, the detection of which ultimately led the Cylon fleet to the new human colony on New Caprica.
A reincarnation of Baltar's Six (named Caprica Six by the others) committed the first incident of Cylon-on-Cylon violence in their history killing a Number Three with a rock in order to save the life of Samuel Anders, who himself was later discovered to be a Cylon.
With Caprica Six imprisoned on Galactica after helping a Sharon (Athena) (Number Eight) escape from the Cylons with Hera, she offered to testify against Dr. Baltar. While in the brig, she has a relationship with Saul Tigh that results in the first Cylon-Cylon pregnancy.
It should also be noted that Caprica Six has a "Head Baltar" which only she sees similar to how Baltar has a "Head Six" that only he can see; Head Baltar serves as a sort of conscience for Caprica Six, but also an advisor in times of trouble or danger, much the same role that Head Six plays for Baltar. This Head Baltar, has also appeared at least once to Baltar himself. Before the true nature of both Head Baltar and Head Six was revealed, there had been rampant speculation that Baltar was a Cylon. In the series finale, both Head Baltar and Head Six turned out to be divine beings (actually referred to as "Angels") manipulating both the Colonials and Cylons into fulfilling "God's plan".
Other important Sixes include Natalie, who originally led the rebel Cylon faction against Cavil's faction before being killed by Sharon Agathon in a misunderstanding, and Sonja, who was elected to represent the rebel Cylons in the Colonial fleet's Quorum of Ships' Captains.Number Sixes are played by Tricia Helfer.
- "Life has a melody, Gaius. A rhythm of notes which become your existence once played in harmony with God's Plan."
- —Inner Six to Gaius.