Is it the fear of meeting your creater knowing you made some poor judgements?
Is it just the fear of not knowing what happens after you leave this world?
Or is it just the fear of not accomplishing something?
Wow... absolutely none of the above.
The only thing that scares me about death is the (seemingly distinct) possibilty that my death won't be swift and/or painless. I'm just not a big fan of extreme pain.
But if I knew for a fact that my death would be painless -- y'know, in my sleep, of old age, while at home, perhaps during my afternoon nap after running a half-marathon -- I would actually look forward to death. There's just nothing about the entire premise of This Life Ending (and the remote possibility of Something Else Beginning) that scares me.