Zombies is tempting but in the end I gotta give it up for Ragnarok! I mean, how many end-of-the-world scenarios feature their divine pantheon going down swinging in a massive free-for-all? Sweet! Plus giant wolfs, giant snakes and giant fire, er, giants. What more could you ask for in an apocolpyse.
Either with written version of Ragnorak (where one god and two people survive to start again) or else the Hindu vision (endless cycles until we somehow get it right)
Anything else is joyless and limited to my mind
Although I often despair, ultimately I believe that mankind will eventually get it right
I mean, seriously, which other ending has snakes, wolves, giants, gods, earthquakes, the loss of the sun and the moon, a new, better world coming out of the event, and the epitome of [Epic] battle?
Both Gliese 710 and Black Holes would be a fascinating way to go, but I decided for Gliese 710. Imagine a star in the night sky which with each passing day grows larger and larger until it surpasses first the sun and eventually the moon in size*. Shame it would either deep fry us or fling us into the cold oblivion of deep space (or both). But still
*Current predictions regarding Gliese 710 predict it will pass us in a relative safe distance, relative 'cause although the star itself will have no real effect on our earth the comets and asteroids it sends hurdling from the Oort Cloud could at the least cause some 'trouble'.