There are two places in Catalyst for storing names, they are the Users section and the Internal Contacts section. The Users section is where you store all of the people that will need to log into Catalyst. All Owners, Contributors, and Viewers will need to have a user account because those roles require the user to be able to log in to complete various functions.
Internal Contacts is where you store the contact information for all employees, including those with user accounts. The Recovery Teams section of recovery plans use the internal contacts section to populate the recovery teams and team contact document sections. If you are using Bullhorn, the internal contacts are also where the contact information for Bullhorn messages are pulled from.