Number 6 appeared in the first scene of the mini-series. She arrived at the treaty point and asked the man waiting there if he was alive. A second incarnation of her is then introduced on Caprica as assistant and lover to world-renowned scientist, Gaius Baltar. Once the attacks on the colonies began, she confessesed that she had been using Baltar all along to access the defense mainframe. Just before the nuclear explosion reached Baltar's home, she sacrificed herself to save Baltar, and downloaded into another body.

Caprica Six is the model who hacked into the Colonial Defense Mainframe on Caprica with the help of Gaius Baltar. Throughout the series she lends her aid to humanity on more than one occasion, having learned a sense of compassion for them after spending so much time among them.SciFiPedia: Number Six

She played an aid to former President Adar named Shelley Godfrey who appeared to frame and expose Baltar to the authorities.SciFiPedia: Number Six

Another model, Gina Inviere, was held captive on the Battlestar Pegasus. Inviere was the former lover of Admiral Helen Cain. Baltar becomes involved in liberating Inviere, and giving her the nuclear warhead she uses to commit suicide.SciFiPedia: Number Six

The model known as Natalie bands together with the Eight and Two models in an attempt to stop the others from lobotomizing the raiders. This creates a rift that separates the cylons down the middle, pitting the Sixes, Eights and Twos against the Ones, Fours and Fives.SciFiPedia: Number Six

There is also a spirit model who is often referred to as "Head Six" because she appears only in Gaius Baltar's subconscious. She has been guiding Baltar inwardly since just after the destruction of the Twelve Colonies.SciFiPedia: Number Six