It depends. That seems to be primary answer when researching this question. This in an artistic endeavor that seems to love hard and fast rules. Proper grammar. Don’t start with the weather. Show don’t tell. Active is better than passive. Write what you know. And, of course, break any of these rules that you want and if the book sells you will be considered a genius.
So, I am going to pose the question to you, dear reader? What do you think?
I am currently writing 1956, the second in my Jazz Jones & January Queen historical PI mystery series. This is told through the eyes of Jazz, occasionally January, and from the perspective of four potential baddies as well. Not to mention the two mysterious henchmen who work for whichever suspect turns out to be the villain. These perspectives are only gently sprinkled in as Jazz Jones takes the lead for the bulk of the book. Jazz has five people, friends and family, who he interacts with and are reoccurring from book one. There are also three clients who have hired Jazz to investigate for them. Of course, there are fleeting characters who might have a name but don’t deserve a credit at the end of the movie.
By my count, the tally has reached sixteen characters in 1955 that the reader must identify with and keep straight in their head. Too many? Too few? Just right? What says you, Goldilocks?
I am also in the process of editing my third in the Chronicles of Max Creed series, Max Creed Takes the Spice Road. In this contemporary international thriller, Max has put together a vigilante band of justice seekers not unlike Robin Hood and his Merry Men. His team includes five regulars, John, Scarlett, Marian, Tucker, and Scads. Their clandestine government liaison, Sevyn Knight, is also the romantic interest. The initial target is Alex Bergmann, but other potential enemies include Bart and Coen Vos, Cleo Dearlove, Pandora, Director Morris, and General Dawson.
By my count, the tally has reached fourteen characters in Max Creed Takes the Spice Road. This is right in line with 1955. Perhaps I have a sweet spot? Fourteen to sixteen?

How Danger Got His Bark
I am also looking for a home for Bob Chicago Investigates, who also happens to be the protagonist. We then adorn him with a cast of colorful characters that include Mandisa, Giggles, and Junko. And we can’t forget his sidekick, Danger, the supermutt. In this mystery, we weave in a spectrum of six potential villains and a mysterious Japanese samurai warrior on horseback.
It appears that the sweet number for Bob Chicago Investigates was twelve. This expands the range slightly, but not much.
Do you, the reader think, that twelve to sixteen characters with significant roles in a mystery or thriller is a good number?
About the Author
Matt Cost was a history major at Trinity College. He owned a mystery bookstore, a video store, and a gym, before serving a ten-year sentence as a junior high school teacher. In 2014 he was released and began writing. And that’s what he does. He writes histories and mysteries.
Cost has published six books in the Mainely Mystery series, starting with Mainely Power. He has also published six books in the Clay Wolfe Trap series, starting with Wolfe Trap. There are two books in the Brooklyn 8 Ballo series, starting with Velma Gone Awry. For historical novels, Cost has published At Every Hazard and its sequel, Love in a Time of Hate, as well as I am Cuba. The Not So Merry Adventures of Max Creed began a new series this past April. Glow Trap is his eighteenth published book.
Cost now lives in Brunswick, Maine, with his wife, Harper. There are four grown children: Brittany, Pearson, Miranda, and Ryan. They have been replaced in the home with four dogs. Cost now spends his days at the computer, writing.














I think it depends upon the following. First are they easy to tell apart? (what do your beta readers tell you about this?) Second do they appear organically, or are their appearances so cluttering that readers spent more time trying to remember who’s who.
I just gave up on a YA book I was given to review because the characters fluttered in and out so often I couldn’t keep them straight.
I think it’s easier to add characters in a series than in a stand alone book. I wouldn’t overpopulate the first book with a ton of sidekicks, but you do have to have people your main characters interact with so it feels like they inhabit a real world. (The people whose names don’t appear in the credits.)
There is only one mystery author I used to read who had so many new characters in each book I had to write them down. But her recurring characters were different enough they became background.
Names make a big difference, too. If the names are too similar or too ‘original’ the reader has to invest precious reading time keeping them straight or figuring out how to pronounce them.
Most of the mystery series I’ve read have a range of recurring ‘background’ characters from around 5-12 and suspects range from 4-9. The main character and main sidekicks are 1-4. That’s a fairly populated book. And if your reader loves the background characters, they better make a realistic appearance in every book! No walk-ons for them.
However, this is me. My book group consistently complains about ‘too many people to keep track of.’ Some of them take the time to write all the characters down, others just complain there were too many. I’m not a good judge because I can usually keep multiple storylines and POV going at the same time. Not the least helpful, I know.
Plenty helpful! And I agree about series which I mostly write. By book two, you should be comfortable with more than a few.
My Goldilocks response is that it is not the number that matters as much as the depth of character knowledge that enables the reader to relate to each of them. As an avid life-long reader I am certain that there were more than 16 important characters in some books that I loved. Just show us enough about each of them to make them unforgettable.
BTW Monica, there are also readers in our book club who write lists of characters as they read – – whatever works.
Background and distinct characteristics for sure! And… maybe a list of characters at the front of the book would be helpful.
I’d say that as long as each is distinct enough for the reader to follow, you’re fine. What do your betas say?
Thus far everybody seems good with my numbers but I was looking to hear from those who might not be regulars. It seems that the answer is always… it depends.