Battlestar Galactica's 15 Biggest Plot Twists And Reveals

9. Boomer Shoots Adama (Kobol’s Last Gleaming—Season 1, Episodes 12-13)

All through the first season of Battlestar Galactica, one of the running subplots concerns Lt. Sharon “Boomer” Valerii coming to terms with the fact that she is really a Cylon and is on Galactica as an unwitting “sleeper agent”. Several times, Boomer finds evidence that she is working to sabotage the Fleet, but works against that programming as much as possible to continue serve the Colonies with loyalty.

All that changes in the closing moments of Kobol’s Last Gleaming, the first season finale. After being congratulated by Adama on accomplishing a particularly vital and strategic mission, Sharon abruptly pulls out her sidearm and shoots the Commander several times in the chest.

The series would later imply that Sharon’s failure to kill Adama was a result of her conflicted nature, but that doesn’t change how shocking the attack is, and how significantly it impacts the trajectory of the show for quite some time.