Arnold Horshack Clyon #10. Kills Adama in season three, uses his head for Walkie Talkie. Has a funny laugh. Nasal voice. Poor student. Anger problems.
Vinnie Barbarino Cylon #12. Gets married to Starbuck, have little Scientologist babies, which are half Cylon, half New Jersey street thug, half blonde butch. In charge of disco night on Cylon home world. Looked down on by other Cylons.
Well, I guess you guys are not gonna be happy with the unknown newly revealed 13th Cylon.
Chris Farley. aka, Fred. Also known as #13. Keeps asking #6 for a neck massage, and no #6, even the tortured one, will do it for him. Lives with Apollo in bachelor pad, doesn't know he is a Cylon. Likes beer.
1st rule in writing cheesy TV shows -- always produce the most dramatic result, regardless of facts or preconditions.
It's totally Adama. People have to remember that this series is ficitional and the writers can of course do whatever they wish, but they tend to go in the direction of the most dramatic(one low-light was the Helo "you cant do that on TV!" cause it's genocide episode), and they've certianly been hinting in Adama's direction.
That being said, if you ask me, by the simple rule I just stated, it won't be the old man. They'll push you and push you in that direction until it's finally revealed that the 5th and final cylon is:
LEE ADAMA
Gods, can you imagine the 90210-style dramatic fall-out from that one !? The old man would work, but Lee would be too juicy to pass up, and I don't think the writers will be able to resist. I mean just the plot line of the old man having to cope with a cylon as a son, the death of his one son prior, his failed marriage etc., may cause people's heads to explode.
I think in the end, it will be revealed everyone on some level has cylon blood -- the whole "everything is happening again" plotline. That is, they'll find earth, the cylons will be destroyed but not without revealing everyone is a cylon on some level (through half-bloods mixing in the general gene pool), and they'll return to Kobol. Then they'll destroy all evidence that they have any cylon bloodline connections, and the cycle can be repeated for them to return as the 12 tribes/colonies once the whole radiation thing goes away on the planets (circa +4000 years). Repeat as necessary.