As the science fiction novelist Nnedi Okorafor takes to the stage at the TEDGlobal conference in Tanzania, she challenges stereotypes before she has said a word. The 43-year-old writer who won the 2016 Hugo award (the Oscars of the sci-fi world) for best novella doesn’t look like much of a geek. Yes, she wears oversized glasses, but Okorafor’s specs are trendy, royal-blue Cat-Eyes, not wiry aviators. And, crucially, she happens to be a black woman.

The Nigerian-American’s success has been applauded as a victory by a community that has long cheered her on from the margins. So when she tweeted on 11 August that she was working on her first project with the comic publisher Marvel, fans were thrilled. (“A Marvel story. Written by a Nigerian woman. Set in Lagos. Superhero’s name: NGOZI. What a time to be alive,” wrote one fan on Twitter) And with a novel, Who Fears Death, to be adapted for TV by HBO (George RR Martin is its executive producer) Okorafor is about to go from the solitary geek reference-point for young African women to everybody’s favourite new sci-fi writer.

Facebook Twitter Pinterest Nnedi Okorafor … don’t call her a geek. Photograph: Beth Gwinn/Must Credit: Beth Gwinn/Writer Pictures

Okorafor is not the only black woman beating a path in the sometimes hostile and isolating world of science fiction. NK Jemisin, who won the Hugo award for best novel two years in a row, was called an “educated but ignorant savage” by the US far-right activist Theodore Beale, who has long railed against the increasingly diverse sci-fi community. Octavia E Butler, probably the best known black female sci-fi writer, has said that she found herself alienated from the characters in the books she read. Okorafor admits to not having read much sci-fi growing up, but, like Butler, struggled to identify with protagonists when she did. “It just seemed like a very sterile, white male world,” she says. “I would migrate towards characters who were alien, or animals.”

Today, though, marginalised black girls and young women with a love for manga, gaming, or robotics, can find each other online. Facebook communities include Black Girl Nerds – which has 126,000 followers – and its offshoot, Black Girl Geeks, which has more than 38,000 followers on Twitter. Black female geeks are also being celebrated on screen: the film Hidden Figures – about the African American mathematicians who played a vital role in the space race – was one of the biggest films at the box office in 2016.

Facebook Twitter Pinterest Venomverse (A Blessing in Disguise) by Marvel. Photograph: Tana Ford/Marvel

Asked how she feels about being called a geek, Okorafor gets animated, but then, as she did on the TED stage, she defies expectations: “For a long time, I refused to call myself a geek or a nerd because I was also an athlete,” she says. “I was always the first kid picked for teams.” She reminisces happily for several minutes about playing dodgeball and semi-pro tennis, and jokes about her phenomenal upper-body strength: “My mum used to throw the javelin. I’ve got her arms. I can do one-handed pull-ups,” she says with a hint of pride.

Raised in the southern suburbs of Chicago, where she and her sisters would be called names and chased by skinheads, Okorafor grew up feeling like an outsider. She has, however, turned that perspective to her advantage, envisaging characters and settings who sharply contrast from their mainstream portrayal; Who Fears Death, for example, is set in a post-apocalyptic Sudan and mixes fantasy with magical realism.

Although she may have been too athletic in her youth to fit the geek mould, Okorafor now finds comfort in the variety within the geek community. At San Diego Comic-Con this year with her daughter, she marvelled at the array of people in cosplay costumes. “We were like: ‘This is awesome. Everyone is just being what they are.’ I like the diversity – there are so many different types of strange.”