For those who have been spending the first half of Battlestar Galactica's final season expecting to see deceased presidential aide Billy Keikeya again - perhaps in a shock revelation as the show's final cylon - then we've got some good news and bad news for you. The good news is, the writers want to bring Billy back as well. The bad news, it's not going to happen.
Speaking during one of the latest podcast commentaries, executive producer Ron Moore explained,
I think we [the writers] were all kind of intrigued about bringing the Billy character back, he was one of our favorites and long dead and it would be kind of cool to see him again in the last season... But there was some scheduling conflict with the actor Paul Campbell, and he wasn't available.
Okay, we'll admit it - This doesn't mean that we have no chance of seeing Billy again; Moore has been known to mislead fans on his podcast commentaries, after all (*coughStarbuck'sdeathcough*). But if he really wanted to keep any potential Billy reappearance a surprise, it's unlikely that he'd start bringing up the subject at all.
If you're wondering why he brought up the subject, it's because the role that equally dead character Elosha played as Roslyn's hallucinatory spiritual advisor in "The Hub" episode was originally going to be filled by a ghost Billy. When Campbell's lack of availability changed that plan, writer Jane Espenson detailed the amount of work that created to fix the script:
In a hallmark of what I consider really fine writing, I just did a global search and replace on the name. I did not change the lines. The only thing I did... I added 'Cue the celestial trumpets.' That one phrase that Elosha has was all I did to change it.
As Moore says in response, "There you go. That's how finely detailed this stuff is."
Battlestar Galactica Commentary Podcast [Scifi.com]