Sex and science fiction have not always been the most obvious partners; combining the two has occasionally defeated even the genre's greatest luminaries. But here are ten authors who successfully brought sex into the future.

1. Samuel R. Delany (1942- )
His 1975 novel Dhalgren is a hugely complex, at times incomprehensible tome reminiscent of the works of Thomas Pynchon. It also showcases every imaginable form of human sexuality, including a long-term polyamorous relationship between the protagonist, his lover Lanya Colson, and a gang member called Denny.

2. Philip José Farmer (1918-2009)
It would be a stretch to say Farmer invented sexual science fiction (especially considering some of the people on this very list predate him), but he did shatter the mainstream notion that sex had no place in science fiction. His 1953 short story "The Lovers" was an overnight sensation for its sophisticated, intelligent depiction of love between a human and an alien, which he followed up with five more stories in a similar vein in his 1960 anthology Strange Relations. He explored unconventional relationships both allegorically within science fiction and literally in his 1962 novel Fire and the Night, which looked at an interracial relationship before they had gained widespread social acceptance.

3. Robert Heinlein (1907-1988)
Nothing if not an iconoclast, Heinlein was a militarist who also passionately believed in free love, at least if his writings are to be believed. It's actually not that hard to reconcile when seen in terms of his ironclad libertarianism, which led him to foresee a future where homosexuality was fully accepted, public nudity was commonplace, and couples were far from the only acceptable number of people for romantic relationships. A noted advocate for polyamory, his works consistently shattered taboos, ranging from relatively mundane topics for the 1970s such as open homosexuality to a full-fledged incestuous romance between immortal time traveler Lazarus Long and his own mother - and all of that was in just one book, 1973's Time Enough for Love. But perhaps his crowning achievement for mixing sex and science fiction was his wonderfully twisted 1959 short story "All You Zombies", in which time travel and a sex change operation allows the story's protagonist to become both his own mother and father, not to mention just about everyone else who appears in the story.

4. Ursula K. Le Guin (1929- )
Le Guin has extensively studied alternative conceptions of gender, both as a critical theorist (in such essays as 1976's "Is Gender Necessary?") and in books like The Left Hand of Darkness. Her novel, published in 1969, considered the Gethenians, a humanoid alien race with no inherent gender. Instead, Gethenians experience the activation of either male or female sexual organs in roughly monthly cycles. To humans, this means they constantly switch genders, although this is a rather quaint notion to the Gethenians themselves.

5. William Moulton Marston (1893-1947)
Marston, the creator of Wonder Woman, may not have the literary credentials of the other people on this list – although he did invent the lie detector test, for what that's worth – but his creation of the first female superhero might have the most pop culture impact. His personal idiosyncrasies, which included living with his wife and girlfriend in a polyamorous relationship, influenced the character's subtext, often leading to Wonder Woman being tied up by other Amazons in situations that evoked bondage imagery (there are entire sites devoted to tracking this very phenomenon). In an era when even recognized comic book geniuses like Will Eisner were content to rip off Superman, it took an uncompromisingly unique individual like Marston to create the first and still the best superheroine, and the medium is infinitely better for it.


6. Joanna Russ (1937- )
One of the first and most important lesbian science fiction writers, Russ confronted sexism head-on in the 1970s with a number of works, both fiction and non-fiction. Her most notable science fiction was probably 1975's The Female Man, which considered four women living on four different parallel universes who then travel between each other's worlds. The different universes include a universe where the Great Depression is still going strong, one that is essentially the same as the real world, another that is a utopian society without any men at all, and a universe where the two genders are literally at war. Russ uses this multiversal backdrop to compare how the various characters' situations influence their conceptions of gender politics and sexuality.

7. Alice Bradley Sheldon (1915-1987)
Better known by her male pseudonym, James Tiptree Jr., Sheldon spent her science fiction career methodically deconstructing supposed boundary lines of sex and gender (she herself was bisexual). She looked at the nature of sex, at times characterizing it as a playful expression of human free will, but otherwise seeing it more as an animalistic force in such stories as "Love Is the Plan the Plan Is Death" and "The Screwfly Solution." Her 1975 novella "Houston, Houston, Do You Read?" dealt with three male astronauts thrown through an anomaly in space to an Earth inhabited solely by women, which Sheldon characterizes as a peaceful but stagnant society. "The Women Men Don't See", on the other hand, depicted two women who used an alien abduction as an opportunity to escape the limitations of their lives on Earth. She depicted sex with a frankness and clarity that was exceptional for science fiction authors of the day, male or female.

8. Olaf Stapledon (1886-1950)
His 1935 novel Odd John is one of the earliest to explore sexual themes in science fiction. Following John Wainwright, a British mutant with extraordinary mental abilities, the novel in part addresses the sorts of relations a superhuman such as John could have with regular people. Although Stapledon never quite comes out and says it explicitly, Odd John almost certainly suggests that Wainwright has sex with both his own mother and a young boy. Ultimately, he concludes that all relations with normal humans are morally wrong on the grounds that his advanced intellect makes any such act essentially bestiality.


9. Theodore Sturgeon (1918-1985)
The same year as Philip José Farmer's "The Lovers" broke new ground with love between species, Theodore Sturgeon shattered the taboo against depictions of homosexuality in science fiction with his short story "The World Well Lost." The story follows a pair of seemingly male and female alien lovers who visit Earth and become celebrities until their home planet demands their extradition. When the aliens reveal to one of the astronauts tasked with bring them home that they are both male and that their crime is love, he sets them free, in part because he nurses a secret love for his copilot. The story was so controversial that it barely got published; the first editor Sturgeon showed it to actively called other editors, demanding they not publish it. Thankfully, Universe magazine saw it differently, and science fiction is infinitely better for it.

10. John Varley (1947- )
His "Eight Worlds" stories depict how technology manages to make homophobia obsolete (well, more obsolete). In a future culture where people can change their gender instantly, there is little room for views that see homosexual relationships as different from heterosexual ones, as a person could wake up one day in one relationship and go to sleep in the other.

Top image from Clyde Caldwell's cover illustration for Farmer's Strange Relations.