countrysteaksauce said:
Nah, that one's too quick.
My favorite end of the world (non earth destruction) scenario involves an Ice-9 type transition (see Cat's Cradle By Kurt Vonnegut).
My favorite end of the world scenario that involves the destruction of the planet itself is General Existance Failure, where every particle that makes up the earth spontaneously ceases to exist (Which, incidentally can happen if certain parts of quantum mechanics are to be believed. Luckily, the odds of it happening on the scale of the eart are so remote that one could expect such an event to occur somewhere in the universe once every few hundred trillion years)