Ursula K. Le Guin, one of the most prolific and influential writers of the latter half of the 20th Century, died at her home in Portland, Ore., on Monday, following several months of poor health. She was 88.

Le Guin, who brought a deft literary and feminist touch to works of primarily science fiction and fantasy, was the author of more than 20 novels (excluding over a dozen books for children and young adults); a dozen books of poetry; several short story collections; and seven books of essays. A mainstay on the supposed shortlist for the Nobel Prize (and a translator of Nobel Prize–winner Gabriela Mistral), Le Guin was one of four writers to have her work collected and published by the Library of America during her lifetime. (Her only company: Eudora Welty, Saul Bellow, and Philip Roth.)

Some of Le Guin's most influential and best-known works include 1968's A Wizard of Earthsea—later adapted, along with other stories from the book's consequent series, by the revered Japanese animator Hayao Miyazaki's son, Goro, into the film Tales from Earthsea, which the author famously took issue with—1969's The Left Hand of Darkness, and 1971's The Lathe of Heaven.

In an interview with PW in 2016, Le Guin explained her passion for the novel, in particular, as a literary form: "When a novel gets going and finds its necessary course, its momentum carries me along like a boat on a river," she said. "If I’m the writer, I’m the pilot, steering the craft the best I can; but I’m also free, because I’m carried by the power and following the way of the water."

That water carried her, more often than she is credited with, into territories outside of speculative fiction; that critics often lumped all of her work under the sci-fi/fantasy banner was, for Le Guin, a bit of a bugbear.

"I’ve never protested when my science fiction and fantasy is called science fiction and fantasy—why should I, when that’s what it is? But a lot of it isn’t, and I do protest having all my work lumped into a genre that only some of it belongs to," she said. "I’ve written for decades in various genres including realism, SF, fantasy, kiddilit, and fable. I published poetry long before I sold a story."

Her work in "kiddilit" culminated, perhaps, in 2012, with the collective republication of her Earthsea series by Houghton Mifflin Harcourt and Simon & Schuster, in tandem. More recently, in 2016, Saga published a collection of her novellas, The Found and the Lost, alongside a short story collection, The Unreal and the Real. Her recent nonfiction includes a Tin House book, Ursula K. Le Guin: Conversations on Writing, and, from HMH, No Time to Spare: Thinking About What Matters.

“Working with Ursula was a privilege, an honor, and a tremendous joy for me, and for many here at HMH and elsewhere in the industry," Naomi Gibbs, Le Guin's editor at HMH, said. "She was an unparalleled writer who lived an extraordinary life. She’s leaving behind an incomparable body of work, and her remarkable spirit.”

Le Guin's legacy is arguably marked most by her creative curiosity and determination to never stop doing the work. She continuously branched out into new forms, and took on various literary projects; in 2015, for example, she launched an online writing workshop in which she was able to teach the craft of writing fiction without having to require students to come to a physical classroom. Despite not having, at 86, the "stamina to write novels...or teach writing students face-to-face," she missed the contact with other writers. Those writers will now, undoubtedly, miss her.