The Nobel Prize in Literature for 2007 was awarded to the English writer Doris Lessing
"that epicist of the female experience, who with scepticism, fire and visionary power has subjected a divided civilisation to scrutiny". Congratulations, Ms. Lessing!
It seems some of Ms. Lessing's works are considered to be speculative fiction. From the official Nobel Prize website (nobelprize.org):
"In the novel series Canopus in Argos: Archives (vol. 1–5, 1979–1984) Lessing expanded the science fiction genre. The series studies the post-atomic war development of the human species. Lessing varies thoughts about colonialism, nuclear war and ecological disaster with observations on the opposition between female and male principles. Among inspirations for the work was the Idries Shah’s school of Sufism that she discovered in the 1960s. Doris Lessing revisited her interest in Sufism in the Time Bites (2004) collection of essays."
"The vision of global catastrophe forcing mankind to return to a more primitive life has had special appeal for Doris Lessing. It reappears in some of her books of recent years: the fantasy novel Mara and Dann (1999) and its sequel The Story of General Dann and Mara's Daughter, Griot and the Snow Dog (2005). From collapse and chaos emerge the elementary qualities that allow Lessing to retain hope in humanity."