We're all aware of the new trend in movies right now, where you make a bunch of different stories with separate characters and settings then tie them all together in a giant cinematic universe. The Avengers helped kick off Hollywood's new obsession, so now we've got movie universes where Captain America is frenemies with Iron Man, Batman fights Superman, and Dr. Jekyll shows up in Tom Cruise's Mummy reboot.
But Hollywood didn't invent this concept of uniting distinct characters and worlds into shared, fictional universes, and it certainly didn't perfect it. Authors have been devising their own multifaceted multiverses for nearly a century and—in the grand tradition of the book being better than the movie—these universes are way more complex, intricate, and entertaining than anything Marvel, DC, or any other movie studio has put on screen to date. Here are some of the most interesting, inspired, and endlessly enjoyable literary universes ever written.