If you've purchased the People Add-On, you can select which role types a person can be. They will be grouped by role type on the event or person list page. 

Go to Groundplan >> Settings and scroll all the way down. 

Selecting the check box means that role type will be available as an option when you assign a role type to a person.

Cast and Artistic Team are included by default. To add more, click the "Add new choice" button.