Natalie
From Wiki Frakr
Yet another smokin' hot variety of Number Six.
This one managed to start a Cylon civil war by telling the Cavils to go and eat some cake, something that was a long time coming. She also decided that the only way the Cylons could survive was to make peace with the humans, a really smart thing to do considering that her race had been responsible for the destruction of the humans.
Anyways, Athena killed her because Hera thought Natalie was her mommy.