You all know where I stand on concepts of "the afterlife", so I am also deeply terrified and depressed by the thought of death. It's THE END. Nothing gets scarier than that, my friends. If there was a reasonable way to become immortal, I would do it before you could say, "an old man's dream"! I just hate the fact that I live in a world where there are so many things to do and knowing that I won't be around to experience 97% of them! All the things I'm going to miss out on.
Think of people who lived back in, say, the 1600's or early 20's. They never got to see all the amazing things we have now! Internet, space travel, Indy, etc. Now try and imagine all the neat gizmos I'M gonna miss out on! I won't be alive to see mankind's first time machine, or see the world's first cloned human, or contact with intelligent extraterrestrial life! It's unfair! If there is a God, then I despise him for giving us such a pathetically short time to live.
And it's made even worse by the fact that I know there will be people that will miss me and mourn me; my passing will cause grief and depression and heartbreak. I know this because my grandfather passed away a few months ago. My regret was enormous, because I never did respect him or think well of him. Imagine how I feel about that now. I'll never be able to tell him I loved him and genuinely cared for him. While he was here, I just kinda acknowledged his existence; I didn't hang out with him or anything. His archaic Christian views and my literal-minded youthful pompousness did not mix.
Anyway, long story short, I'm terrified of the inevitability of death. Now if only there was a way to make Horcruxes without committing murder and splitting my soul and becoming a snake-man! ARGH!