Linda Adams wrote, I have 25 essential characters.
Others have written about the dozen or more characters they have in their work.
I'm not criticizing except to say that in my current work I have something like a grand total of 4 essential characters - 2 of them protagonists, 1 of them a Deputy Sheriff, and 1 a terrorist.
I think it depends on what you mean by essential. If we're talking essential to the plot, then i would differ with you on the examples below as to who is essential.
Take '
The Icarus Hunt' for example:
Timothy Zahn's The Icarus Hunt has 2 essential characters (the 2 protagonists whose names I can;t remember right now).
[SPOILERS FOLLOW. IF YOU HAVEN'T READ THE STORY YOU MAY WANT TO AVERT YOUR EYES NOW]
For the plot to work in this story, a lot more characters are needed than the two protagonists (Jordan and Ixil).
Cameron, the archaeologist who made the find and tricked Jordon into captaining the ship, is essential, even though he doesn't make much of an appearance. Without him there is no plot.
The Patth, as a race, are essential, otherwise there'd be no danger.
The other crew members (5 or 6, can't quite remember which) on the ship, in their varying lengths of appearance, are essential, because without them there could be no mystery as to who the mole is. There couldn't even be a mole, which takes out a substantial plot-related subplot.
Brother John/Ryland, the guy who Jordan is apparently working for, could also be termed an essential character, because he provides another subplot, and is essential to the big reveal, as is Antoniewicz, who is alluded to throughout the story, but not actually met until the climax.
And General Graym-Barker, who also isn't revealed until the end, but who Jordan often calls during the story, is essential too. In fact, he almost plays a deus ex machina type roll, which is almost as frustrating for me as Jordan's (the narrator) lack of reliability.
So that would be 12 characters essential to the plot, by my counting, and by my reckoning of essential, which isn't necessarily right
