How can I create a user with no posting privileges

I know this seems like an odd request - but bear with me. I would like to create a user that can’t create posts. I want to be able to create a Discourse profile for an organization, separate from the person responsible for that organization.

An example would be YoyoDyne Inc., as a separate entity from the YoyoDyne CEO. I would like the CEO to be able to create topics and posts, but I would not want YoyoDyne Inc. to be able to post. The CEO would want to link to their company profile when they wanted to highlight the company, instead of linking to their own profile and posting history.