Feminist science fiction is a subgenre of science fiction (abbreviated "SF") focused on such feminist themes as: gender inequality, sexuality, race, economics, reproduction, and environment. Feminist SF is political because of its tendency to critique the dominant culture. Some of the most notable feminist science fiction works have illustrated these themes using utopias to explore a society in which gender differences or gender power imbalances do not exist, or dystopias to explore worlds in which gender inequalities are intensified, thus asserting a need for feminist work to continue.

Science fiction and fantasy serve as important vehicles for feminist thought, particularly as bridges between theory and practice. No other genres so actively invite representations of the ultimate goals of feminism: worlds free of sexism, worlds in which women's contributions (to science) are recognized and valued, worlds that explore the diversity of women's desire and sexuality, and worlds that move beyond gender.

— Elyce Rae Helford

Feminist science fiction is a sub-genre of science fiction (SF for short) that focuses on theories that include feminist themes, for example gender inequality, sexuality, race, economics and reproduction. Feminist science fiction spans a wider range than science fiction itself, covering fantasy, utopia and dystopia, horror (such as Anne Rice's vampire stories). Marleen S. Barr says that what is described as feminist ‘SF’ is not really ‘SF’ at all, because it is not concerned with ‘hard science’ but with women's drive for power. Hard science fiction is of course a subset of science fiction. She thought we needed to use a term like feminist fabulation.

Fantasy literature is de facto a privileged genre for tackling feminist themes. Because it allows to reflect on the future, on the possibilities of humanity and science, this literature allows all progressive and innovative ideas to coexist. So, to qualify as feminist science fiction, the stories must carry a political message, that of challenging the male/female paradigm in society. With this in mind, in the early 1990s the American feminist fanzine Aurora SF published a list of ten levels of feminism to measure the political content of a text. This graduation of the political message ranges from simple questioning of patriarchal society, to egalitarian discourse between the sexes, to systematic criticism of men, to the establishment of feminist and lesbian utopia.

In her book In the chinks of the world machine: feminism and science fiction, Scottish author Sarah LeFanu distinguishes between feminist SF and women's SF insofar as the latter, while having a certain influence on the development of science fiction in general by rejecting sexism and featuring female heroes, does not make feminist demands.

Feminist science fiction (SF) distinguishes between female SF authors and feminist SF authors. Both female and feminist SF authors are historically significant to the feminist SF subgenre, as female writers have increased women's visibility and perspectives in SF literary traditions, while the feminist writers have foregrounded political themes and tropes in their works. Because distinctions between female and feminist can be blurry, whether a work is considered feminist can be debatable, but there are generally agreed-upon canonical texts, which help define the subgenre.

As early as the English Restoration, female authors were using themes of SF and imagined futures to explore women's issues, roles, and place in society. This can be seen as early as 1666 in Margaret Cavendish's The Blazing World, in which she describes a utopian kingdom ruled by an empress. This foundational work has garnered attention from some feminist critics, such as Dale Spender, who considered this a forerunner of the science fiction genre, more generally. Another early female writer of science fiction was Mary Shelley. Her novel Frankenstein (1818) dealt with the asexual creation of new life, and has been considered by some a reimagining of the Adam and Eve story.