There are occasions when a crowd is desirable. Rock concerts, parades, football games. But not even the Astrodome has an infinite seating capacity, and a novel or story is a lot more limited than the Astrodome. How many characters can you have in a story? A novel? A single scene? How many can, or should, be fully described and developed?
These aren't trivial questions. Overpopulated fiction can be so confusing that readers put the story down. Under-populated novels can seem claustrophobic or boring. You want the right number of characters for your particular work.
Characters in a scene: Part I
In general, limit speaking parts in a scene to the characters who genuinely need to be present. You might, for instance, have two people talking intently in a restaurant. If the waitress, wine steward and old friend seated across the room don't have a part to play in the scene, mention them in the same way you might mention furniture, but no more. "The waitress took our order," or "The wine steward recommended a very nice Burgundy." That's enough. The focus stays on your two diners.
If, on the other hand, one point of the scene is that the two characters never get to say important things at this dinner, then dialogue is justified for minor characters, as in the following scene I've created:
"Karen," Paul said, "I really wanted to ask you if-"
"Is everything okay?" the waitress said, grinning brightly.
"Yes, fine. Karen-"
"Would you like more breadsticks?"
Karen said, "No, thank you, we're fine."
"Your entrees will be out shortly." She removed the salad plates and left.
"Paul, I'm so glad you invited me here tonight because I have something I need to say, too. Last month when you-"
"More wine?" the steward asked, materializing beside their table.
Paul and Karen will never get their announcements completed, and we will never see this waitress or wine steward again. But because they have a purpose in this scene besides background, the author is justified in making them actual presences.
So the answer to the question, "How many characters should you have in a scene?" is twofold. For spear-carriers with no speaking parts, an unlimited number. For characters with dialogue, the fewest number who have a reason to be there. That might be two, or four, or 10 (if it's a long scene).
Characters in a scene: Part II
How do you put in those multiple characters without confusing the reader? Let's look at how author Connie Willis does it in her novel Passage. Joanna has stopped by to pick up Kit, who lives with her elderly uncle, to see a movie:
Kit led the way into the library. Mr. Briarley sat in his red leather chair, reading a book. He didn't look up when they came in.
A gray-haired woman in a shirtwaist was sitting on the couch. She reminded Joanna of Mrs. Troudtheim. She had the same friendly, no nonsense, "I can survive anything" manner, and she even had a tote bag full of olive-green-and-bright-purple yarn. What is it with crocheting? Joanna wondered. Do people automatically go color-blind when they learn to crochet?
"Now, you have my cell phone number," Kit said to her. "I borrowed my cousin's until I can get one of my own," she explained to Joanna.
"Right here," Mrs. Gray said, patting the breast pocket of her dress.
"And you'll call me if there's anything," Kit said anxiously. "Anything at all."
"I'll call you," Mrs. Gray said, pulling out her crocheting. "Now, you go have a nice time, and don't worry. I've got things under control here."
"Go?" Mr. Briarley said, shutting his book and marking the place with his thumb. "Where are you going?"
This is a bridge scene, not dramatic in itself but necessary to the plot. It goes on for another page and is never confusing. That's because the author adheres to several guidelines:
Orient readers to all characters' positions. This tells us who's present, so we don't wonder halfway through the scene where that character suddenly came from. It also helps us visualize the scene, which in turn helps keep everyone straight. We know that Mr. Briarley is in the red leather chair, Mrs. Gray on the sofa, Kit and Joanna standing.
Give characters actions as well as speech. This, too, aids in visualization. Mrs. Gray crochets, Mr. Briarley marks his page with his thumb, Kit leads the way to the library.
Don't let characters go too long without saying or doing something. Whatever the length of a scene, make sure everybody chimes in periodically so we don't forget who's there.
Differentiate speech to the extent possible. This would obviously be easier in a scene with one Cockney policeman, one Southern good ol' boy, and one Irish fishmonger. In most scenes, however, your characters will share a general style of speaking. You can still make sure they don't sound interchangeable by paying close attention to each person's individual concerns. Kit is anxious about leaving her uncle. Mrs. Gray, the hired caretaker, wants to reassure Kit. Joanna is the observer of everyone else, her major role in the novel.
Make sure readers always know who's speaking. This may require more "said tags" than usual.
Characters in short stories
The ideal for a short story is the same as for a scene: Include the fewest number of characters that will carry out your plot. The shorter the story, the lower that number should be. That gives you more wordage to develop each character.
There is a lower limit to this, however. It's very hard to write a story with only one character. This is because readers want to see your protagonist interacting with others. We come to know people through their interpersonal relations. Even Jack London, in his classic short story To Build A Fire, gave his lone Arctic explorer a dog so that the character would have someone to talk to.
How many of these two or more characters should be point-of-view characters? Purists say: One POV character per story. I count myself among the purists. This is because we're all used to experiencing reality from inside one head, our own, and so a one-POV story feels more real, as well as more unified.
However, some stories cannot be told from only one POV. No one character is present at all crucial events, or the protagonist must die, or you simply need the richness of a dual POV. In that case, weigh what you gain against what you sacrifice.
Characters in novels
Novels have much more space than short stories, which gives you more leeway with the number of characters you can include. Even "furniture" characters can be described and given speaking parts to develop background or atmosphere.
In Dorothy Eden's historical romance Melbury Square, for instance, a character named Mr. Shepard appears twice, each time for a dialogue one page long. Shepard is an art expert at Sotheby's who phones the now elderly heroine, Maud Ponsonby, to say that a portrait of her, supposedly painted by her dead father, is actually a fake. In the second scene, he brings the portrait to her house so that Maud can reach the same conclusion. Since Shepard himself is not important, both scenes could have been handled with brief paragraphs of exposition. So why does the author give Shepard two quick scenes before retiring him forever? Consider this passage from his first appearance:
"Why do you want me to see the painting?"
"Because we have some doubts about its authenticity. It might be a copy."
Papa being copied! He would be livid with anger. She was angry for him.
"Who would find it worthwhile doing that?"
"Anybody. Didn't you know that your father's paintings are bringing up to twenty thousand pounds nowadays?"
"I haven't sold one lately," she said dryly.
"Well, if ever you have occasion to, remember that. Especially if they are portraits of Maud."
She had only three left. Twenty thousand pounds. She seemed to be sitting on a fortune. But of course she would never sell them. Even if she were as near starving as Hessie thought she was ...
"So could we ask your opinion, Mrs. Ponsonby?"
A touch of her old tartness returned. "I thought you people knew everything."
Even with dramatization, Shepard is still a cipher. But Maud isn't. This conversation helps characterize Maud in her old age: still tart-tongued, still passionately possessive of her portraits, still fiercely identifying herself with the father who ruined her life. In a novel, there is room to introduce minor characters, use them in this way and discard them.
How many characters, minor and major, should populate a novel? There's no answer to that question. It depends on the novel's length, on its scope, and on the style of the writer. Tom Wolfe crams a huge, colorful cast into Bonfire of the Vanities and A Man In Full. In contrast, Judy Blume's Summer Sisters, which covers far more time than either Wolfe book, contains only a handful of well-developed characters. Your call.
The number of POV characters, however, is more restricted. Readers don't like to bounce in and out of several dozen characters' heads; it induces a literary equivalent of motion sickness. As a result, the novelistic convention has evolved to one POV character per scene. If you need to suddenly see the action through a different character's eyes, start a new scene.
None of this is difficult once you've had a little practice. And if you exercise a little fictional crowd control, the reader will benefit through increased pleasure in your stories.