ChrisHurst

MyWebsiteAdvisor

This plugin allows you to watermark your previously uploaded images using a PNG image file with transparency as well as text signature. 
The user friendly settings page allows for control over the appearance of your watermark. 
You can set your watermarks to always be a specific percentage of the target image. 
This plugin will add the watermarks to ALL of the images in your WordPress uploads directory.
Please BACK UP all of your uploads via FTP before using this plugin!
<a href="http://mywebsiteadvisor.com/plugins/bulk-watermark/" rel="nofollow ugc">Upgrade to Bulk Watermark Ultra</a> for advanced 
watermark features including:
<ul>
<li>Fully Adjustable Text and Image Watermark Positions</li>
<li>Adjustable JPEG Image Output Quality</li>
<li>Highest Quality Watermarks using Image Re-sampling rather than Re-sizing</li>
<li>Lifetime Priority Support and Update License</li>
</ul>
Check out the <a href="http://www.youtube.com/watch?v=XkFXBjfzw2I&hd=1" rel="nofollow ugc">Bulk Watermark Plugin for WordPress Video Tutorial</a>:
<iframe loading="lazy" class="youtube-player" width="750" height="422" src="https://www.youtube.com/embed/XkFXBjfzw2I?version=3&rel=1&showsearch=0&showinfo=1&iv_load_policy=1&fs=1&hl=en-US&autohide=2&hd=1&wmode=transparent" allowfullscreen="true" style="border:0;" sandbox="allow-scripts allow-same-origin allow-popups allow-presentation allow-popups-to-escape-sandbox"></iframe>
Developer Website: http://MyWebsiteAdvisor.com/
Plugin Support: http://MyWebsiteAdvisor.com/support/
Plugin Page: http://mywebsiteadvisor.com/plugins/bulk-watermark/
Compare Watermark Plugins: http://MyWebsiteAdvisor.com/tools/wordpress-plugins/watermark-plugins-for-wordpress/
Video Tutorial: http://mywebsiteadvisor.com/learning/video-tutorials/bulk-watermark-tutorial/
Requirements:
<ul>
<li>PHP v5.0+</li>
<li>WordPress v3.3+</li>
<li>GD extension for PHP</li>
<li>FreeType extension for PHP</li>
</ul>
To-do:

Bulk Watermark

Adds an image and/or text watermark to all uploaded images, using PNG images with transparency.

Protect Uploads

The uploads directory is where the files of the WordPress library are stored. Unfortunelty, this directory is not protected. A person who wants to see all your library could list it instantly going to : http://yourwebsite/wp-content/uploads . This plugin will hide the content by adding an index.php file on the root of your uploads directory or by setting an htaccess which will return a 403 error (Forbidden Access).
<ul>
<li>Depending on your server setting, the htaccess option could be disabled.</li>
</ul>
New in Version 0.7.0:
<ul>
<li>Site Health checks: See at a glance — under Tools → Site Health — whether your uploads directory is protected from browsing, what server you are running, and whether any risky file types are sitting in your uploads folder.</li>
<li>WordPress 7.0 ready: Fully tested on WordPress 7.0 and PHP 8.3.</li>
</ul>
All features:
<ul>
<li>Directory Protection: Stop visitors from browsing your uploads directory (index.php or .htaccess 403).</li>
<li>Image Watermarking: Add text watermarks to your uploaded images with customizable position, opacity, and font size.</li>
<li>Right-Click Protection: Prevent users from right-clicking to download or save your images.</li>
<li>Password Protection: Secure individual media files with passwords. Multiple passwords can be set for each file with custom labels.</li>
<li>Access Logging: Track who accesses your password-protected files with detailed logs including IP address and user agent.</li>
<li>Site Health Checks: Built-in protection status tests with actionable advice.</li>
</ul>
Need more protection? <a href="https://protectuploads.com" rel="nofollow ugc">Protect Uploads Pro</a> adds image watermarks with bulk operations, expiring download links, role-based access with server-level enforcement, hotlink protection, download analytics, and a Protected Download block.
Available languages:
<ul>
<li>English</li>
<li>Français</li>
<li>Español</li>
<li>Italian (thanks to Marko97)</li>
</ul>

Do not download. The plugin has been changed not too long ago and it now infects your wordpress installation, and possible spreads itself to other sites if you are on shared hosting.

It's a virus

Protect your uploads directory. Prevent browsing, add watermarks, disable right-click, and password-protect files. For more information, visit protect …

Bulk Watermark vs Protect Uploads