There are two great tasks to complete:
First of all, you come up with a list of characters (from the protagonist to the man that walks on the street and asks about the time in chapter 8). It is impossible to think about all the characters during the planning stage. Since some of them won’t even exist until you start writing, but you may have an idea of who will be the main characters. This list of characters will increase and be completed as you make progress with your first draft.
On the other hand, it is necessary to know the characters, by writing profiles or small-biographies for each of them. Knowing everything about your characters before writing a single word is very important. Not doing this means not having the basic material to convince readers that these are “alive” beings, and this won’t say much about your reputation as a novelist.
What needs to be used from the small biographies, for you to write and create each main character? I’ll tell you how you can create characters.