Shared Universes: What They Are and Why They Work

Shared universes can be incredibly exciting to write, and make it easier to sell multiple books.

Cat Webling
Cat Webling
Person about to start running

One of my favorite fantasy series of all time is the Xanth series by Piers Anthony. This set of more than thirty books covers the magical land of Xanth from its initial settlement to its interaction with the modern non-magical world; each story in the series follows a new character and tells a new story, but they all happen in Xanth. 

This is what’s called a shared literary universe, and it’s one of the most interesting things a writer can do with their work. But what counts as a shared universe, and how do you go about setting one up? What if you want to join a universe that already exists? 

Let’s explore what it takes to create or join a shared universe in fiction.

What is a shared universe?

In literature, a shared universe means that two or more standalone stories canonically take place in the same exact overworld setting, within the same continuity. That means that these stories have the potential to influence each other and even have characters, settings, and plot points cross over and interact. 

Here’s how that works: I write a story about a fictional version of Earth where my protagonist in Kentucky discovers she has magical powers and, with the help of a mentor, goes on a quest to save her town from destruction. In my next book, I write about a boy from New York who discovers he also has magical powers, and, having heard what happened in Kentucky, decides to seek out the help of the same mentor, only to find that he’s gone missing. Along the way, there could be cameo appearances from characters from the first book.  Each book has its own unique plotline and different characters, but it’s clearly happening in the same place; Protagonist B has heard about Protagonist A’s storyline, and can directly interact with its characters and locations. It’s not just a similar Earth - it’s the exact same one for both of these characters. 

Lots of stories do this; many authors create a sort of continuous history of their written world by creating standalone books that follow the same universal rules as their previous work. It’s a great way to reuse interesting systems and locations without having to write a direct sequel to your previous novel. Not all stories need sequels, but all worlds have a wealth of stories available to tell.

Are shared universes and multiverses the same thing?

You may have thought of the term ‘multiverse’ when reading that explanation above. Is that the same thing? No, but it’s a similar concept, and it’s often used in tandem with shared universes. Marvel comics have played with the concept a lot, and its shown up in recent TV series like Wandavision and Loki.

A multiverse is a series of universes inside of the canon that are connected but running in parallel to each other. The universes might have extremely limited interactions and may be mirror images of each other or run on different rules entirely. Usually, if the idea of a multiverse is brought up, it’s going to be used at some point for a major piece of the plot.

While characters can interact with characters from other plotlines in both a shared universe and a multiversal canon, a multiverse lets characters meet different versions of themselves (like Star Trek’s mirror universe) while a shared universe does not. Additionally, while all stories told across a multiverse have a shared universe (in the outside-of-the-story sense), not all shared universe stories exist in a multiversal setting. 

Examples of shared universes

It might be easiest to show you what I mean by “shared universes” by peeking at some of the most popular literary and cinematic shared universes. 

Tolkien’s Middle Earth

JRR Tolkien is the grandfather of modern fantasy, and it’s largely because of his richly detailed world of Middle Earth, a fantastic world with dragons, wizards, dwarves, elves, and more. Tolkien wrote many, many stories about Middle Earth, from its ancient history (in the Silmarillion) to the War of the Ring (in The Hobbit and the Lord of the Rings saga), all of which happen in the exact same continuity - it’s a direct timeline of events that you can trace logically from one story to the next. 

The Stephen King Universe

Though they all work as total standalone novels (save for the sequels of course), Stephen King’s massive body of work across multiple genres actually all happens in the same continuity and canon universe…well, universes. The foundation of this is set up in King’s Dark Tower series, a fantasy epic spanning eight books that follow a multiverse-traveling gunslinger and his various companions as they attempt to reach said tower and save all of the worlds at once.  This tower is where all of the evil from all of the horror novels he’s written get their power from - so the resurrected pets, evil clowns, twin ghosts, and killer cars are all drawing from the same source.

The Riordanverse

Rick Riordan is probably most famous for his Percy Jackson and the Olympians series, but his literary universe extends far beyond the top of the Empire State Building. The Riordanverse happens in the same continuity across multiple series, often with overlapping characters appearing as protagonists in one story and side characters in another. In Riordan’s shared universe, all gods from all mythologies around the world are implied to exist - so far, we’ve seen the Greeks, Romans, Egyptians, and Norse, just to name a few. Apparently, these gods exist together in overlapping fields of influence but generally have their own territory - as is noted in the Kane Chronicles as a fun nod to the events of the original PJO series. 

“So you can't live in Manhattan?' she asked.

Amos's brow furrowed as he looked across at the Empire State Building. 'Manhattan has other problems. Other gods. It's best we stay separate.” - The Red Pyramid

The Conjuring Universe

Hardcore horror movie fans will likely think of The Conjuring when they hear mention of shared universes. This series of movies - including all of the movies in the Conjuring franchise, the Annabelle movies, The Nun, and The Curse of La Llorona - centers on Ed and Lorraine Warren, or the dramatized versions of them depicted in the movies, as they deal with supernatural entities in their lives. Some of the movies focus on the Warrens themselves, while others branch out to tell the origin stories of some of the monstrous entities they encounter. Everything is happening in the same fictionalized version of Earth where evils like this are confirmed to exist.

The Marvel Cinematic Universe (MCU) and DC Extended Universe (DCEU)

The Marvel Cinematic Universe, from Disney-owned Marvel Studios, is one of the most popular shared universes in the modern era, with forty installments and counting, following such iconic characters as Captain America, Iron Man, Spider-Man, The Hulk, and The Mighty Thor. As shown in the Avengers series, all of these movies are happening in the same continuity - even with the time travel and multiversal shenanigans - though this has been true of Marvel’s character base since the comic books first started coming out. There are lots of different comic lines with their own continuities, but the universes are all connected via a multiverse, with lots of opportunities for characters to team up, like what happened in Avengers: Endgame

The same is true for Warner Bros DC Cinematic Universe, which hasn’t been as big at the box office but does have just as many hard-hitting names and stories - including Superman, Batman, The Flash, and Wonder Woman - driving its films, which again, stem from lines of comics that share a multiverse.

The Monsterverse and Universal Monsters

Yet another movie buff popular series is the Monsterverse. The Monsterverse began with the original Godzilla and King Kong movies and became official with the release of King Kong vs. Godzilla in 1962. It expanded to include other kaiju like Mothra, Rodan, and Mechagodzilla, and the subsequent reboots of the movies have been built on the fact that, in this version of Earth, all of these mega-monsters exist together. Universal also had their own cinematic universe featuring iconic creatures like Dracula, Frankenstein, The Wolf Man, and the Invisible Man. Universal tried to relaunch this concept again as the Dark Universe, but when The Mummy flopped, they canceled it. (Tom Cruise's Mummy, not Brenden Frasier’s.)

Star Wars

The galaxy far, far away created by George Lucas has spread across every form of media. Star Wars may have started as movies, but now there are animated series like The Clone Wars or Rebels, live-action tv shows like The Mandalorian and Andor, comic books, novels, video games, audio dramas, and more. Each explores different characters and parts of the timeline, and allows for different styles and genres to play out in the same setting. For example, The Book of Boba Fett at times feels like a live-action cartoon, while Andor mixes a retro science fiction aesthetic with noir and spy thriller vibes.

How to create a shared universe

So, how do you go about creating a shared universe? The best thing you can do is stay organized, which is why planning out your series is so important.

Create a universal canon

Your first course of action is to create the universe that your characters will share. I covered this in more depth in our worldbuilding template, but here’s the basic rundown on how to build a fictional universe: 

  1. Decide what’s going to inspire your world - are you writing a story that’s set here on Earth (or a close approximation) or in some other fantastical setting?
  2. Do some research to decide what your setting is going to look like - if you’re setting things on Earth, learn a little more about the time and place you’re writing in, and if you’re not, learn a little bit more about the kinds of geography and potential history that might lead you to where your story starts.
  3. Answer the big questions - these are your who, what, when, where, why, and how questions about the way this particular world works. This will help you set the rules for your universe. You’ll also want to decide on the scope of the story (are these books individual tales or a continuous overworld saga?).
  4. Create an outline - you should do this for every novel in the series, and also for the series as a whole (this is where having an awesome series bible comes in handy).
  5. Drop your characters in - get writing and fill in the details about your world as they come up!

Tell different stories with a constant setting

Now that you have a universe to put your characters in, you’ll want to decide how you want to put them in. This is where a shared universe series diverges from a regular sequential series; shared universe books don’t have to have anything to do with each other beyond existing in the same timeline of events. You don’t have to share characters between books - you don’t even have to acknowledge the existence of other stories between books! As long as your stories are happening in the same general setting (even if they’re happening on different planets in that same setting), you’re good to go.

That being said, shared universes offer you the unique opportunity to make plot holes intentional. A great way to get inspiration for future stories is to look at your previous works in this universe and find the unanswered questions in them. What ever happened to this character? Why did this ancient war start in the first place? Where did this monument come from? You can jump forward and backward in time and all over the place in space to answer these questions, meaning you’ve got endless possibilities for new stories and spinoffs.

A shared universe also created the potential for epic crossover events bringing together characters from different books and series. Imagine bringing together your own versions of the X-Men, Fantastic Four, and Man of Steel to face a threat to the universe only their combined power can defeat? Author Thomas K. Carpenter did this with his Hundred Halls universe, bringing together characters from five different series for an epic trilogy to cap it off.

Have an underlying ruleset between books

Continuity is important in a shared universe, which means that the only thing that needs to stay consistent between books is the physical setting and the timeline of events. If a war happens before the creation of a particular country in one book, you can’t set another book in that country before the war. 

The exception to this is intentional time or multiversal travel shenanigans. That being said, you should still have a consistent set of rules for how time travel and the multiverse work in your setting, and stick to them, even if your characters are hopping and skipping all over the place within it. Setting rules and limits is how you increase the stakes of a story; if there are no rules, there are no reasons why your characters can’t do anything and everything they want immediately.

How to market a shared universe

Marketing strategies will depend heavily on your genre and budget, but there are a few tips you can use to market a shared universe series.

  • Include an “Also By” page in your back or front matter with the name of your shared universe and a list of the other books in the series. This lets readers know that, if they enjoyed the book they have, there’s more for them to explore.
  • If you have excellent reviews from your other books, you can include a “Praise for the [Name] Universe” page in your front or back matter.
  • Advertise the books as a set, with copy that focuses on the shared universe and ties the stories together.
  • Create connected short stories and other bonus items to include as free reader hooks.

How to join an existing shared universe

While many shared universes are run by one author, many are not. Sometimes, an author with an established universe will bring in other writers to help grow the universe even more than they could on their own. A couple examples of this include M.D. Cooper’s Aeon 14 universe, or J.N. Chaney’s Renegade Star universe. Joining in a shared universe project can help expose your writing to the audience of a similar author who already has an established fanbase. To me, this is a win-win situation; you get to write what is essentially canon fanfiction for a literary world you love and readers of that series get a new story to enjoy. 

To join an existing shared universe, you’ll need to first get the rights to write in the setting from the current rights holder. This might be another author or a publishing company; you can usually find out who owns the rights by going to the copyright page of any installment in the shared universe series.

Create a book proposal for the story you want to write in that universe (at the bare minimum, a synopsis of your story) and bring it before the rights holder. If they sign off on your idea, you’ll want to work with them to ensure you’re following the rules they have set for their universe while you’re writing. From there, you’ll probably have to collaborate to establish a release timeline and marketing plan that works for everyone involved.

Each shared universe experience is going to be different, so if you want to write for a particular universe, the best thing you can do is ask the rights holder about it. The worst that can happen is they say “no,” so there’s no harm in trying. It is probably best to only try this after you have a few published books of your own under your belt. Rights holders will want to see samples of your work, and having a track record for finishing and releasing books will help show you’re serious about your pitch and can be counted on to follow through with it if brought onboard.


Shared universes can be incredibly fun for writers to explore. Our real world has more than seven billion people on it at any given time, each telling their own stories with their own challenges, crises, successes, and quests; imagine how many stories there are to tell in an entire populated universe!

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