Dune, by Frank Herbert's 1965

2012, WIRED US readers voted Dune the best science-fiction novel of all time. It's also the best-selling of all time, and has inspired a mammoth universe, including 18 books set over 34,000 years and a terrible 1984 movie adaptation by David Lynch, his worst film by far. A hopefully better effort is currently in production, directed by Denis Villeneuve. The series is set 20,000 years in the future in galaxies stuck in the feudal ages, where computers are banned for religious reasons and noble families rule whole planets. We focus on the planet Arrakis, which holds a material used as a currency throughout the Universe for its rarity and mind-enhancing powers. Lots of giant sandworms, too.