Among the initial phases of any case is identifying the persons and entities involved and understanding how they relate to one another and to the issues and events in the case.
This entails (1) identifying (and keeping track of) the people involved; (2) understanding their relationship to one another; and (3) exploring their relationship to the events and other aspects of the case.
I use Tinderbox to keep a running list of every name I encounter in my initial investigation, whether learned from documents or in witness interviews. I also use Tinderbox to track my notes on these people, questions about them and information to obtain. Tinderbox also allows me to display how these people are related (if at all).
Each of these three functions is handled by a separate aspect of Tinderbox.
First, I create a new note for each person or entity I encounter. This is infinitely superior to simply listing each person in a text file or in the text box of a single note.
I use a prototype note to ensure that all of these notes share the same essential characteristics. (I typically use the convention “protoName” for my prototypes, thus the person prototype is “protoPerson.”) This way, I can add a badge, color, or otherwise set the appearance of each person note. I typically put these people into a container, but they could just as easily stay on the top level of my Tinderbox document.

Using map view to show character relationships. The head icon on each note is a badge.
Regardless of where I store these characters, viewing them in map view is very useful for arranging the people in relation to one another. Perhaps two ‘characters’ in the case are married. Perhaps two others were involved in a key transaction. In addition, some people will be more important than others. Once I know this, I can make those notes larger or color them more distinctly or give them a badge to denote their special status. I typically include adornments within this map view to visually connect people as important or as targets of an investigation or what not.
Of course, often in the course of a case, you want to look over a list of all of the people involved. Perhaps you’re looking for one person in particular or just want to run through everyone in sequence. Outline view is the best tool for this job. While I could simply view the container of characters in outline view for a rudimentary list, this is less useful if there are other note types in the same container (e.g., events, questions, notes about issues, or legal elements to prove) because the list will include all of the notes in that container, not just the people.
It is far more effective to create an agent to collect all of the characters in a separate container. The advantages are (1) to collect all of the characters regardless of where they are created; (2) to only collect characters (as opposed to questions, issues, etc.); (3) and to sort them without disturbing the organization of the notes in map view.

The settings for a Cast of Characters agent.
To do this, I create an agent, name it Cast of Characters or something similar, and set the query to collect all of the notes where “Prototype=protoPerson”. I then set the agent to sort the results by the last name (Sort by = name; last word).
Thus, when I want to see a list of the characters, I simply click on the Cast of Characters agent and open it with a new outline view (under the Views menu item).

Outline view presents a list of all of the people in a case.