What a companion book is
A companion book is a book connected to another book or series, but it is not simply the next installment. It may share a setting, a cast of characters or a theme with the original, while telling a different story or offering information about the world of the first book.
The term is used in two common ways:
- Companion novels are works of fiction that share a world or characters with another novel, often with a new main character.
- Companion guides are books about a book or series: encyclopedias, handbooks, art books or reference volumes.
Because the word is used loosely, publishers and readers do not always agree on where the line falls. When in doubt, check the cover or the publisher’s description.
Companion vs sequel, prequel and spin-off
| Term | What it usually means |
|---|---|
| Sequel | Continues the same story after the first book ends |
| Prequel | Takes place before the original story |
| Spin-off | Follows a secondary character or element into a new story |
| Companion novel | Set in the same world or connected by characters, but can be read separately |
| Standalone | Complete on its own with no required connections |
The boundaries blur. A spin-off that centers on a side character can also be called a companion, and a prequel that can be read on its own may be marketed as a companion. What readers care about is mostly whether they need to read the earlier book first.
Types of companion books
Same-world novels with new characters
These books return to a setting readers know but follow someone else. They are often easy entry points because you can start with the companion and then go back.
Same-story, different viewpoint
Some authors retell part of a story from another character’s perspective, or cover events that happen in parallel. Orson Scott Card’s Ender’s Shadow, which runs alongside the events of Ender’s Game from a different character’s viewpoint, is often cited as an example.
In-world reference books
Some companion volumes are written as if they exist inside the story’s world. J.K. Rowling’s Fantastic Beasts and Where to Find Them and Quidditch Through the Ages are presented as school library books from the Harry Potter series. The Tales of Beedle the Bard is another volume in that vein.
Guides and encyclopedias
Fan-focused handbooks, atlases and concordances help readers keep track of characters, timelines and maps. Large fantasy worlds are especially likely to have these. They sometimes include an index and sidebars, similar to the features described in our overview of the parts of a book.
Annotated or study companions
Study guides and annotated editions sit alongside a classic text to explain context and vocabulary. They are a separate kind of companion, closer to commentary. For more on that, see our guide to annotation categories and how to annotate.
Companion book examples
A publisher’s young adult list highlights several companion pairings. Described briefly and without spoilers:
- Jenna Evans Welch, Love & Luck is presented as a companion to Love & Gelato. It follows a character connected to the first book’s cast on a new trip.
- Cassandra Clare and Wesley Chu, The Red Scrolls of Magic is tied to the Shadowhunters books and focuses on two characters readers already know.
- Sandhya Menon, There’s Something About Sweetie is a companion to When Dimple Met Rishi, featuring a relative of one of that book’s leads.
- Mila Gray’s small-town novels are described as sharing a tone and setting, with a new story and characters each time.
- Jonathan Maberry, Broken Lands begins a new series in the world of Rot & Ruin.
- Tamora Pierce, The Immortals quartet takes place in Tortall, the same world as her earlier Lioness quartet, with a new main character.
Other well-known examples include the in-world Harry Potter books and Ender’s Shadow mentioned above. Details like series order and publication history can differ by edition and region, so check the publisher’s listing.
What to call books that go together
Books that go together are usually called a series. More specific terms depend on the number of books:
- Duology for two books
- Trilogy for three
- Quartet for four
- Saga or cycle for a long, sprawling set
- Shared universe when separate series or standalones are set in the same world
A set of companion novels with changing leads is sometimes called a “companion series” or a “series of standalones”.
Do you need to read the original first?
Often not, but it varies. A few points to consider:
- Companion novels are usually written so that they can be read on their own, but earlier characters may appear as cameos or references.
- Reading the original first can add richness, and sometimes spoils parts of it.
- In-world reference books and guides generally assume you know the story.
- Check the publisher’s description or reader reviews for a “can be read standalone” note.
How to find companion books
- Look at the “also by” page or series page in the book you just finished.
- Search the author’s website for reading order. For an example of a reading-order guide, see our Jack Carr book synopsis and reading order, or the Shadow and Bone series summary for a fantasy series.
- Ask a librarian or bookseller, who often know series connections.
- Use reader communities and book clubs, where members often know which titles connect. Our guide to how online book clubs work explains where to find them.
- Check the cover and description for words such as “companion”, “set in the world of” or “a novel of”.
Frequently asked questions
What are multiple books that go together called?
A series, or more specifically a duology, trilogy, quartet, saga or shared universe, depending on how they connect.
What are 5 books everyone should read?
There is no universal list, and people disagree widely. A better approach is to pick books that match your interests, then follow the series or companion titles you enjoy.
What is the 50 page rule?
It is a reading guideline, often credited to librarian Nancy Pearl, suggesting you give a book around 50 pages before deciding whether to continue. It is a rule of thumb for deciding whether to keep reading, not something specific to companion books.
Can companion books be read in any order?
Many can, but it depends on the series. Publisher series pages usually indicate a recommended order.