End of the World scenarios are a popular thematic device in just about every medium. It takes the notion of the disaster movie and expands it to encompass the whole of humanity or even the whole of creation.The usual format is for a portents to appear and be investigated and shown to be leading up to the destruction of the earth, a colonized planet or universe. This gives a time-frame of sorts that informs the story arc. The genre also covers themes such as disease reducing the modern infrastructure of the world we know back to a primitive state by depopulation.
There are a number of related themes that often tie in as a cause of the impending doom:
One way or another, humanity's days are numbered.
Some notable extinction event arcs are: