Genre fiction tends to be plot-driven. There are two types of story: the character-driven story, and the plot-driven story. Think about the classic detective story. How does it begin? With a corpse. The thriller? An ordinary person comes under threat from an extraordinary character or organisation. The love story? Two people meet and must face obstacles in order to be together. Science fiction has similar genre expectations that are related to plot, and this includes generic characters – the kinds of characters that are common to the genre (in fantasy this would be kings, barbarians, wizards, thieves). These are archetypes. An archetype is a recurring or typical specimen or symbol/motif. In contrast, there is the stereotype. This is an idea or convention that has grown stale; that lacks originality or individuality. The heart of any story must ultimately be its characters, and these characters must be distinct.

• The robot – a term first used by the Czech playwright, Karel Čapek, the robot has many roles in science fiction, and usually as a secondary character. They are comedic (Marvin the paranoid android in The Hitchhiker’s Guide to the Galaxy), malevolent (Maria in Metropolis, the terminator in Terminator), and face the same dilemmas we face (the short span of life and what existence means in Do Androids Dream of Electric Sheep/Blade Runner, the yearning for freedom in Alex Garland’s Ex Machina).
• The unknowable – see the great intelligent planet in Stanislav Lem’s Solaris and in the Andrei Tarkovsky film of the book. Also, the ‘ghost’ in Interstellar.
• Funny foreigners – any science fiction tale by Moebius, the alien invaders who are quickly bamboozled by the humans they have conquered in Christopher Anvil’s humorous Pandora’s Planet, the silica based life form that poos silica bricks in Stanley G. Weinbaum’s A Martian Odyssey, and the cantina scene in Star Wars.
• Strangers – aliens that are a central part of the story, and that are often humanoid but also ‘other’ (Isserley in Under the Skin by Michel Faber), or are similar to a life form the reader or audience finds accessible (the octopus-like entities in Gareth Edwards’ film, Monsters, the pitcher plant-like carnivorous Triffids in John Wyndham’s Day of the Triffids).
• Computers – Hal 9000 from Arthur C. Clark’s 2001: A Space Odyssey (arguably the most ‘human’ character in the Kubrick film, and a modern version of Shelley’s Frankenstein’s monster), the Earth in Douglas Adam’s The Hitchhiker’s Guide to the Galaxy, Mother in Ridley Scott’s Alien.
• Humans – these characters are often ordinary people in extraordinary situations/worlds. They might be members of a dynasty (as in Frank Herbert’s Dune) but their concerns are still accessible to the reader. They are often outsiders (Winston Smith in George Orwell’s Nineteen Eighty-Four, Snowman in Margaret Atwood’s Oryx and Crake).