4. Boomer Shoots Adama Battlestar Galactica ('Kobol's Last Gleaming Part 2')
A lot'a folk gettin' shot in these... Syfy's 'Battlestar Galactica' re-imagining (hands down the greatest show of all time, anywhere, I don't care what you say) takes fourth place with the gripping finale to the show's first season. By this point, we're all well and truly aware of the fact that Lt. Sharon 'Boomer' Valeri is a fracking cylon, and she's just starting to discover that fact for herself. Her fears are confirmed on a mission to destroy the Cylon Base-Star, where she runs into multiple copies of herself, but why they are all naked is a discussion for another time. Having succeeded in destroying the enemy ship, she and her co-pilot/navigator return to Galactica as heroes. Adama goes to shake her hand, and BOOM; she pulls her side arm and empties a few rounds in his chest. Never mind us, even she didn't see it coming. Yet happen it did, and we're left with the pretty gruesome and show-stopping sight of Adama bleeding out on the CIC war table. Then suddenly, cut-to-black. See you in six-to-eight months, suckers!