Yet again, the WriYe blogging circle provides me with a subject that makes me go blank. Aside from a brief reference to a scary-beyond-all-reason girl called Stella, I've never really re-used a universe. I don't even know if that counts - it's just a convention of my writerly multiverse that girls called Stella are always bad news. She's appeared in three separate stories, most recently as the personification of my Inner Critic.
So, let's talk about other people who've re-used a universe.
Sara Douglass has done it - Beyond the Hanging Wall, the Axis trilogy, the Wayfarer Redemption and Threshold were all apparently set in the same universe. Then all Ms Douglass' favourite characters from those books were drawn together for the DarkGlass Mountain trilogy. At least I assume they were her favourite characters. Surely she couldn't have made StarDrifter so appealing if she didn't love him.
Stephen King did it, setting quite a few books in the same region of Maine. Then there was the Dark Tower...
As a representation of the writerly multiverse, that series was just incredible. Characters were drawn from everywhere and fitted into the story as if they'd been written especially for the part. It was huge and insane and wonderful. The Dark Tower made me take a look at the things I read and the things I write and start thinking that maybe I really could just walk away from high fantasy and never look back.
Clive Cussler can come next. You don't have to read every Dirk Pitt novel in sequence... or at least I hope not, since I've only read about half of them. They're fun. You can get a handle on the characters pretty quickly and you don't have to be an expert in anything to get a good idea of what's going on. You could go to the bookshop now and pick up almost any of them and read it without ever having seen any of the others.
I'm a bit hesitant to add Terry Pratchett and Discworld to this list because while I haven't read all of them I always feel like I should have. It's not that you can't pick up a random one and read it so much as that every book you read means you can put a few more pieces of the puzzle together and enjoy the other books even more. That's part of what makes Discworld so awesome, actually - you don't have to read it in sequence and you don't have to read all of it, but if you do it adds more and more layers of awesomeness with every book you read.
Okay, so that's "same universe, different series" as represented by a few authors I read. I wish I had a lot more to say on this topic now. What are your thoughts?