Terry Pratchett’s flat world on four elephants on a giant turtle: 41 novels between 1983 and 2015, and probably the longest sustained satire in literature. It runs in strands you can start almost anywhere: the wizards (from The Colour of Magic), the witches (Wyrd Sisters), the City Watch (Guards! Guards!), Death himself (Mort), and the industrial-revolution arc (Going Postal). Common advice: do not start with the first book, Pratchett was still warming up. The usual doors in are Mort or Guards! Guards!.