Which American author's novel 'The Left Hand of Darkness' won both Hugo and Nebula awards?

Ursula K. Le Guin wrote the novel The Left Hand of Darkness, which won both the Hugo and Nebula Awards for Best Novel.

Published in 1969, the science-fiction novel is set on Gethen, a planet whose human inhabitants are ambisexual rather than permanently male or female. Its narrator, Genly Ai, is an envoy from the Ekumen who becomes closely connected with Estraven, a Gethenian political figure. Their journey gives the novel its emotional and political center.

The book won the Nebula Award in 1969 and the Hugo Award in 1970, with both honors recognizing it as the best novel of its award year. Le Guin became the first woman to win both awards for a novel. A common mix-up is confusing this work with her Earthsea books, including A Wizard of Earthsea, which belong to fantasy rather than the Hainish science-fiction universe.

The novel is especially notable for examining gender, politics, loyalty, nationalism, and cultural misunderstanding through speculative world-building rather than conventional social realism.