railmedia

Very lightweight plugin which if activated, it locks down the website for public access. Visitors will be prompted with the wp-login.php page where they should log in to access the site. Useful for under construction websites.

WordPress Require Login

Denis Yanchevskiy

Allows you to make post, page, custom post elements required: title, content, featured image.
After installing the plugin, you need to go to the Settings -> DCO Post Validator to specify the required elements.

DCO Post Validator

Allows you to make post, page, custom post elements required: title, content, featured image.

WordPress Require Login vs DCO Post Validator