List of SF genres and sub-genres

A series of genres & sub-genres, with sometimes conflicting definitions.

Based on setting

Based on earth era

Historical SF

• Alternative history (usually imagines the world as it would have been had a major event occurred differently)
• Secret history (secret conspiracy or organization or species; supposedly normal life persists. Secret history stories pop up particularly in science fiction. They are, effectively, a subcategory of alternate history; but rather than supposing some major event went another way, they suppose a group of manipulators, hidden conspirators, minor events, unknown events, that conspired to get us here, today, to the place we are.)
• Alternative universe (very similar to earth-normal but tweaked in significant, or insignificant, ways)
• Time travel

Based on plot

• Mystery
• Western
• Romance

Based on plausibility

• Speculative fiction - what if this happens?
• Science fiction - This could theoretically happen
• Fantasy - this could not happen

Based on sensibility / literary mode

• Horror
• Prose
• Poetry