Create user permission
This module allows users to create new users without granting them the ability to administer all users. This enables more granular control over user creation, allowing specific roles to create users with lower-level roles.
This module makes it possible to make people be able to create users, without granting them the permission to "administer users".
Combined correctly, you can then make people create users of roles "beneath" them in the role hierarchy, both without passing out that permission and without enabling users to register themselves.
If you want to watch a video tutorial for this module, you can check it out here.
Drupal 7 version
To use the Drupal 7 version you have to have a core patch applied (currently). This patch can be found at https://www.drupal.org/project/issues/drupal/2922852
Warning! The Drupal 7 version has some compatibility issues with LoginToboggan module, and more specifically if the logintoboggan_immediate_login_on_register setting is set to TRUE.
A patch to LoginToboggan is proposed as a workaround: https://www.drupal.org/project/logintoboggan/issues/2929843