Science fiction has a number of common concepts and themes that have been reused by numerous authors. Some have become cliches, and only truly novel treatments of them gain attention, whilst others have become "part of the furniture", ie they can be included in a story without much explanation, because readers are all already familiar with the core concept.
In alphabetical order:
- Aliens (see Aliens in fiction)
- Alien invasion
- Benevolent aliens
- First contact
- Principles of non-interference (eg Prime Directive)
- Xenobiology
- Androids
- Arcologies
- Artificial intelligence
- Clones
- Colonisation
- Cosmology
- Cryonics
- Cyberpunk
- Economics
- Post-"Age of Scarcity" (arguments over how to distribute resources irrelevant since anyone can have anything they reasonably want, eg The Culture, and the problems of excessive wealth as in Frederik Pohl's The Midas Plague)
- Fantasy fiction
- History
- Alternate history
- History repating itself (either on long or short scales)
- Scientific prediction of the future (eg Psychohistory)
- Secret history
- Horror fiction
- Interstellar travel
- Faster than Light
- Very very nearly light speed
- Ursula LeGuin's NAFAL ships, and the Twin paradox
- Much slower than Light
- Moving planets
- Language
- Alien languages (eg Klingon)
- All humans speaking one language (possibly Esperanto)
- Current human languages evolving/splitting
- The Sapir-Whorf hypothesis being strongly true (eg Babel 17 by Samuel R. Delany or The Languages of Pao by Jack Vance)
- Universal Translators
- Mind
- Beings of pure mentality
- Mind uploading
- Mind control
- Memory removal/editing
- Hive minds
- Solipsism
- Artificial intelligence
- Mutants
- Parallel worlds
- Planets in Science Fiction
- Politics
- Post-apocalyptic science fiction
- Posthumanism
- Enhancement of the organism
- Body modification, including genetic modification
- Cyborgs
- Enhancement of the organism
- Psi powers
- Technology and its side effects
- Shapeshifting
- Simulated reality
- Teleportation
- Time travel
- The Grandfather paradox -- e.g. Can someone go back in time and kill his parents before they beget the killer?
- Virtual reality