Unit Zeta

The Unit Zeta Human Cylon Models, also known just as Zetas are one of the 12 Human Cylon models developed in the 25 years between the Cylon War and the Cylon attack on the 12 Colonies of Kobol. (Battlestar Prometheus)

In Battlestar Prometheus
The Unit Zetas where the first (and so far only) Human Model introduced in the story. They where among the models sent to infiltrate the 12 Colonies in order to pave the way for the Cylon invasion.

Kelly Zeta
This model was sent to form a relationship with Dr. Robert Kelly who was working as a member of the Colonial Defense Ministry on Caprica. The exact extent of the relationship between Kelly and this Zeta is unknown, while they had a sexual relationship, it is unknown if either truly cared for the other.

This Zeta used her relationship with Dr. Kelly in order to access the Defense Mainframe. She used it in order to create a backdoor into the Defense computer systems for the Cylons to use when they began the attack on the colonies.

However the Zeta was not yet ready to abandon Dr. Kelly, she returned to him and told him her true nature. After this, the Zeta informed him of the existance of 11 other Human Cylons and left him with one more mystery by telling him that he had to find someone called the Hybrid, however the nearby nuclear strike kept Dr. Kelly from questioning her on that note.

The fate of this Zeta is unknown after the nuclear strike, but it is presumed that she was downloaded into another body.

Other Zetas

 * A Zeta was involved in the attack on the Armistice Station.