We can now determine who the final Cylon is.
Two important clues have been given in the show within the last few episodes that make it clear who the identity of the Final Humanoid model is.
Colonel Saul Tigh was able to impregnate Caprica Six during one of their love-making sessions within the Brig on Galactica. Since Saul Tigh is a known humanoid Cylon and Six is a known humanoid Cylon, one would assume that the whole “Cylons cannot have babies” rule would apply. However, Saul did impregnate Six, meaning that the Final Five can have babies.
D’Anna Biers (Number Three) tells Laura Roslin that there are only four of the Final Five in the colonial fleet. So, where could that final Cylon be?
The answer is clear. The Final Cylon is not in the Colonial Fleet.
There is only one other place that Colonial forces (the only life in the universe) are currently stashed.
Find the location. Make a list of those present. Oh, and refer to Point 1. I think we have a good candidate for Final Cylon.