From Goodreads:
Dystopias, alien invasions, regenerated dinosaurs, space operas, multiverses, and more, the realm of science fiction takes readers out of this world to tackle all-too-real issues, including oppression, bigotry, censorship, and the horrors of war. To celebrate the most inventive of genres, we're exploring readers' 100 most popular science fiction novels of all time on Goodreads.
...To create our list, we ran the data to reveal the most reviewed books on our site. Additionally, each title needed at least a 3.5-star rating from your fellow readers to join this list. And ... in the case of multiple titles from the same series, we chose the one with the most reviews.
Here are the top science fiction novels on Goodreads, listed from 1 to 100. We hope you discover a book or two you'll want to read in this lineup, whether it's a classic of the genre or one of the newer entries to sci-fi.