The average number of characters a book has varies based on the author and the genre of the book. Some novels, such as "Robinson Crusoe," may only have a few characters. Others, such as the high fantasy of George R.R. Martin, have hundreds. Generally, novels have at least three characters. These are primary, secondary and tertiary characters.
A primary character is the protagonist or hero. This is the character who drives the story and the one readers care about most. It is this character's motivations and goals that give the novel its plot. A secondary character can have varying amounts of depth. These characters cross paths with the primary character and influence his or her journey. Often, a secondary character is the antagonist who opposes the actions of the hero and gives depth to the story. Tertiary characters are characters created out of necessity. They add little to nothing to the story and fill roles such as populating the world.
When writing a novel, the amount of characters used should be the minimum it takes to tell the story. Often when working out a plot, writers combine characters to make the story less complicated. It is better to have fewer characters with more complex emotions than many one-dimensional characters, advises StandoutBooks.