Apocalyptic science fiction is a sub-genre of science fiction that is concerned with the end of civilization, through nuclear war, plague, or some other general disaster.

Post-apocalyptic science fiction is set in a world or civilization after such a disaster. The time frame may be immediately after the catastrophe, focusing on the travails or psychology of survivors, or considerably later, often including the theme that the existence of pre-catastrophe civilization has been forgotten or mythologized. The fall of civilization may also be the fall of a space based civilization. This plot device allows writers to write soft science fiction while accounting for the lack of technological advancement and thus remain relevant to the present day no matter how far in the future the events are set.

• See Apocalyptic and post-apocalyptic science fiction