Confession time: I've always had trouble killing characters. In my early projects, it was a personal running joke. When I finally managed to kill off a narrator's significant other, I was pleased with myself ... until the story took a turn and I realized it made perfect sense to bring him back to life. So much for that.
I've gotten better, if you want to call it that, over the intervening years - at least, with novels. In short fiction, all bets are off. Killing off a novel character is still a rarity for me.
On the other hand, death, the afterlife and those who have passed on play a role in a lot of my novels. Journal of the Dead is set in a world where souls jump into the minds of their murderers. One of the plot threads in Butterfly's Poison involves the ghost of the dead king. There's even some patter in Who Wants To Be A Hero? involving death, taxes and afterlife. And even after her death in Unnatural Causes (this is not a spoiler, as it is part of the ten-second pitch), Cailys continues to influence the story. Vil and Iluenn cope in part through their differing visions of the afterlife.
I suppose that what it boils down to is, for me, death is transient and neutral, so its main consequence is all of sudden, I have a character / toy I can't play with any more. That's no fun! Ahem. Instead, as a writer, I always keep in mind that there are worse things than death ...
So don't let your guard down when reading my works, thinking the characters will get off unscathed. I have plans in the works.