“Restrict Registration” is a plugin for WordPress that allows you to control 
who is registering on your blog. This plugin uses simple blacklists and 
whitelists to define who can register for your blog, and who is restricted. Use 
simple literal matching, flexible asterisk wildcard matching, or powerful 
regular expression matching: it’s your choice! The options page is clear and 
easy to use. Set your lists, and you’re done!
This plugin was inspired by WP-Deadbolt, but has been completely rewritten and 
redesigned, and several new features have been added.

Restrict Registration

Use simple blacklists and whitelists to control who can and cannot register on your blog.

asadowski10

Extend of user-groups plugin, this plugin allows you to restrict access to users groups in back-end and front-end on page.

User Groups Restrictions

Extend of user-groups plugin, this plugin allows you to restrict access to users groups in back-end and front-end on page.

Restrict Registration vs User Groups Restrictions