I have only ever killed off one character. It was actually a very difficult thing for me to do because of personal reasons. Those who know me, know the whole situation surrounding it. Long story short, I did it thinking it would help me get some closure to losing someone in RL... it didn't really but that's another story. I would like to think it had meaning.
As silly as it may sound, I don't think I could write anything else like it again in game.