Come to think of it, one of the reason's for 24 having such a downfall in recent seasons is that the show, so caught up in shock-tactics/"no character is safe!" antics, had all but killed off all its best characters by the end of S3.
And then of course there is the most retarded example of this, the premiere of S5, where they killed off 3 (well, 2 now that Tony is back) of the most loved characters in a span of 5 minutes. Palmer's made sense as a catalyst for the season, but Michelle and Tony seemed like nothing but pure shock value. Michelle was one of my other favorite characters.