For every lit author like Cormac McCarthy, who borrows science fiction themes, there are ten authors who start out writing science fiction, and then become beloved of literary hipsters. Here's a partial list.
It's funny, when you think about it, that so much attention gets paid to the McCarthys, Atwoods, Lessings and Roths of the world, who are known for their lit writing but try their hand at speculative fiction here and there. There are really just a handful of them who've made an impression, whereas there are tons of SF authors who've gone the other way - and yet, people seldom talk about it.
Mary Shelley, H.G. Wells, Jules Verne and Edgar Allan Poe are all writers whose names come up a lot when you talk about science fiction authors who have become beloved of the lit-mongers. To some extent, I think Shelley, Wells, Verne and Poe predate the genre-ification of SF, since they were writing at a time before the term was invented. In any case, they've all long since been embraced as fully literary. (Well, mostly. Of Poe, critic V.S. Pritchett famously said he was "a second class writer, but a fertilizing exclaimer.") "I get the sense that Wells in his day was a "novel of ideas" guy/polemicist who was later gerrymandered into SF," says Douglas Wolk, author of Reading Comics.
H.P. Lovecraft was clearly a genre writer in his time, thanks to his association with Weird Tales and other magazines. Nowadays, he's the subject of a book-length essay by fancy-pants French guy Michel Houellebecq, and the prestigious Library Of America has collected his stories.
Stanislaw Lem. A few science fiction authors have gotten published in the New Yorker, but Lem was a regular fixture there for years. Lem's satires, in which Ijon Tichy encounters weird time paradoxes, surrealistic societies and philosophical dead-ends, are tailor made for the lit crowd.