Many novels, particularly the lengthier multi-volumes in the fantasy field, are packed with characters, some major, some minor, others appearing so intermittently that they can be easily forgotten. Many readers will remember a full cast list with no problem; or they simply go with the flow and, especially with a well-written story that has an engaging narrative, hardly ever need to check the list of characters, or dramatis personae . Nevertheless, having something that can be referred to when you’re unsure just who is who can be invaluable. Think Lord of the Rings or Game of Thrones and you can see what I mean. Or you may be reading mainstream or crime or any other genre: the arguments for the dramatis personae may still apply.
You can read the full essay over on the Penkhull Press website. Don’t forget when you do: these are guidelines, not rules.