18. AGENT CAITLIN TODD (Sasha Alexander), NCIS (2005)

If you were a fan of NCIS in 2005, you were aware someone was dying in the season 2 finale, you just didn't know who. Cut to the team's shootout with terrorists, and Caitlin diving in front of Gibbs (Mark Harmon) to take a bullet. Turns out she was wearing a vest. She stood, and viewers exhaled as Gibbs told her she did good. ''Wow,'' she said. ''I thought I'd die before I ever heard a compliment —'' and gunshot. With a single bullet to the forehead from hated villain-sniper Ari (guest star Rudolf Martin), she was gone. —Mandi Bierly