Ursula K. Le Guin, the award-winning author known for her fantasy and sci-fi novels, has died at the age of 88.

Le Guin breathed her last at her home in Portland, Oregon on Monday, Jan. 22. Her family confirmed the news of her death via the author's official Twitter account.

"She was a peaceful warrior," her son Theo Downes said in a statement on Tuesday, Jan. 23. "But for us as family, her legacy as a wife and mother is just as extraordinary." He also noted that the cause of death was not immediately known.

Ursula K. Le Guin's Career

Le Guin's books have sold millions of copies across the globe and have also won her several prestigious awards. The author published her very first novel Rocannon's World in 1966 and was one of Le Guin's many works set in the universe of the technological Hainish Cycle, an alternate/future history. In 1968, Le Guin released the award-winning fantasy children's novel A Wizard of Earthsea, a book that became known as one of her finest works and has been widely influential within the genre. However, it wasn't until the release of her book The Left Hand of Darkness in 1969 that she became a household name. The novel established Le Guin's status as a science-fiction author and won her numerous awards including two of science fiction's highest honors: the Hugo and Nebula awards. The book, which is set on a planet where gender does not exist, has been in print for nearly five decades.  In addition to writing over 20 novels, Le Guin has also authored a dozen poetry books, more than a 100 short stories, seven collections of essays, 13 books for children and five volumes of translation. Moreover, she has also penned a guide for writers.

Tributes Pour In On Twitter

Shortly after reports of Le Guin's death emerged, several acclaimed authors including the likes of Neil Gaiman, Laurie Penny, Stephen King, and John Scalzi took to social media to offer their condolences.