Whatever her name is, because it was such a sad and pointless yet pivotal moment for everything.

Most other times, I don't really care too much. Of the shows you mentioned, Battlestar Galactica is the only one I've watched, and Dee's death did nothing for me. I also saw Fringe, but unlike the other responders, Ella's death didn't leave me overly distraught. It was a bit sad, but I dunno. I never saw her growing up, she was just this fully developed adult walking around and acting like she's the daughter of the two main characters who look hardly a few years older than her. It kinda just made her feel like an ordinary character for me, rather than the daughter of the two protagonists. And she was certainly cool on her own merits, it's just she never really had a chance to spread her wings and show her full capabilities, without being overshadowed by her parents.

Those are the only ones in tv that I can think of, without giving it more than a minute's thought.