Workflow User Roles

Author

Create pages.  Not able to change workflow, but can look at workflow tab.  Can change display security.  Author's pages will be listed in the Dashboard Pages Awaiting Review when workflow is configured.

Editor

An editor can approve pages. This user cannot change workflow steps, but can add authors and any prior-step editor. Editor's pages will be listed in the Dashboard Pages Needing Review when workflow is configured.

ItemAdmins (Item Administrator)

ItemAdmins can change workflow and assign settings to any editor and author roles.  They cannot add New Item Admins.  They can assign values but NOT New Group Item Administrators.

You can manually add a new group in order to assign Author Group permissions to multiple users for workflow.  If you don't need a Group "Author,” you can assign specific users as Authors when configuring workflow on an item.