As many fine gentlemen have noted before me, I would say...
#1 = Reality/Nature/The Universe. Has. It. All. Since it includes everything else! We're scr*wed. Literally. For all infinity... :|
The most deadly aspects of the aforementioned are probably:
- Man himself (humanity);
- the laws of physics / the physical laws (we still don't know them well enough!);
- ignorance, stupidity, human sins, thinking that we are right;
- believing in our species' superiority while any deadly virus or other biological threat might kill us all off relatively easy;
- other natural disasters...;
- being evil;
- being good;
- not giving a fuck about anything;
- the feeling of doom & giving up;
- not pursuing progress, prosperity and health for all life, including ourselves...;
- religions, governments, politicians, bureaucracy, real conspiracies, aliens, monsters, ghosts, dudes from alternative universes...;
- starvation, poverty, social alienation, global injustice...;
- hypocrisy, double standards, human inequalities...
I think that those mostly sum and wrap everything up...
P.S. Good topic for a thread, well done.