- An NBC pilot called 17th Precinct. Created by Ronald Moore, and starring Battlestar Galactica and Caprica alumni such as Esai Morales, Jamie Bamber, James Callis, and Tricia Helfer, about the titular precinct in a world with magic instead of science. It ended up getting passed over by NBC. Fortunately, it has now been leaked online in all of its what-might-have been glory.
- If what Ronald D. Moore says on the podcast commentary for "Kobol's Last Gleaming Part 1" is to be believed, how he originally wanted it to end was for Baltar to go down a long dark tunnel in the ruins on Kobol, at the end of which he finds Dirk Benedict, who introduces himself as "God". Oh, and Baltar also hears an actual Jimi Hendrix recording playing during all this, and when "God" asks him if he recognizes the tune, he says "yes". And Moore claims to have had absolutely no idea what any of this was supposed to have meant, but the other PTB were barely able to talk him out of it.
- The original plan for Season 4.5 had Ellen as a villain, Tory having more involvement in Baltar's cult, which would turn violent, Cavil's forces attacking during the mutiny, Gaeta and Zarek's group leaving the Fleet in their own ships, and Boomer coming over and convincing more Cylons to join the Fleet. It was revised during the Writer's Strike hiatus.
- In the season one episode "Bastille Day", Cally was originally raped and murdered by the prisoner holding her captive. The writers decided to change this because it would make the scene where Cally bites the guy's ear off seem pointless.
- The publication of the "bible" document drawn up before Season One went into production revealed some plots that never made it into the series, among them:
- Lee developing romantic feelings for Laura, and this complicating his relationship with his father further, because Bill also has feelings for Laura.
- Laura being harsher on security matters than Bill, and Bill following her advice because Lee agreed with her.
- Bill declaring martial law and putting Laura in the brig because he felt she had gone too far to suppress dissent in the fleet rather than because of a disagreement over the Arrow of Apollo.
- Six joining in when Gaius has sex with Kara.
- Laura banning abortion in Season One (she did it in Season Two), and allowing birth control only for women with jobs like Viper pilot.
- The Cylons having let Galactica escape to find Earth.
- Helo telling Sharon things about the Colonial military that are then instantly known by the Cylons pursuing Galactica.
- Tyrol becoming Baltar's archnemesis.
- Baltar naming people who are threats to him as Cylons.
- Baltar positioning himself into a position of leadership with the people unhappy with Roslin's administration (this kind of happened in Seasons Two and Four).
- "The Face of the Enemy" went through a few revisions. Originally Gaeta's old lover would have been a Six and his boyfriend would have been Narcho (Sebastian Spence). As Narcho was a mutineer, their relationship wouldn't have ended. Actor availability changed that. The Cylon passengers would have been a Six and an Eight, both involved in the killings, and they would have a scene talking about the killings while the others slept. Tricia's unavailability changed it to two Eights, with one killed off at the start to reduce the amount of computer trickery needed. In retrospect, as Jane Espenson says in the podcast, this was a boon, because the sororicide made it less obvious that Sweet Eight was the killer.
- Harrison Ford auditioned to play Commander Adama, and really wanted the role. Unfortunately, the producers couldn't meet his pay requests, even after he drastically cut his usual pay scale. Ed Harris also tried out for the role.
- Jon Cryer not only auditioned for the role of Gaius Baltar, he actively campaigned to get it.
- Season Three was going to have a storyline about the Saggitarons having been far more successful than others during a famine on New Caprica, due to their holistic farming methods, leading the other Colonies to band together and steal their food. This would have tied in with Baltar's mysterious whisper to Gaeta that made Gaeta try to kill him (later repurposed for the "Face of the Enemy" webisodes) and would have made the notoriously bad episode "The Woman King" not seem quite so random and pointless.
- Gaeta was originally intended to be killed by The Circle in the Season 3 episode "Collaborators", but the writers felt it was just too dark to have the other characters willingly execute an innocent man. That, and it would likely have destroyed audience sympathy for those involved.
- Due to scheduling conflicts, the one-off character Bulldog did not return.
- In one draft of the finale, Helo and Athena would've died, leaving Hera to be raised by Baltar and Caprica Six.
- Tom DeSanto and Bryan Singer, with the full support of Glen A. Larson, originally proposed directing a faithful continuation of the 1978 series set some 20 years later, using as much of the original cast as possible. The project got as far as having scripts written, cast hired, sets built and filming scheduled. Then 9/11 happened, which caused delays, and then both DeSanto and Singer left the project to work on X Men 2, as the delay to filming BSG was interfering with their contractual obligations to start the movie by a certain date. Then Sci-Fi Channel tore up all the pre-production sets, without warning, overnight, whilst green-lighting the series we all know now. This page gives some idea as to What Could Have Been.
What Could Have Been / Battlestar Galactica (2003)