omerk

<a href="http://fancybox.net/" rel="nofollow ugc">Fancybox</a> is a tool for displaying images, html content and multi-media 
in a Mac-style “lightbox” that floats overtop of web page. It was built using the jQuery library.
This plugin inserts the necessary elements required to run Fancybox on your blog. It also groups 
images within posts using rel attributes. (Based on the code found on <a href="https://wordpress.org/support/topic/automatic-adding-lightbox-rel-and-group-to-images-in-posts" rel="ugc">this</a> 
forum thread)
To disable Fancybox per post: Add a custom field called ‘nofancybox’ and set it’s value to ‘true’. 
Instructions on how to add custom fields to posts can be found at <a href="https://codex.wordpress.org/Custom_Fields" rel="nofollow ugc">this</a> 
codex article.

Fancyboxify

This simple plugin enables Fancybox on image links. It groups all images within a single post and can also be disabled per post.

Stefan Hüsges

<a href="https://github.com/tronsha/wp-lightbox-plugin" rel="nofollow ugc">Source Code on GitHub</a>
<h4>Documentation</h4>
Select “Media File” at “Link to” when creating a gallery.
If the plugin is active, the images are now open in the lightbox.
The plugin requires PHP 5.3.2 or newer.
This plugin uses <a href="https://github.com/lokesh/lightbox2" rel="nofollow ugc">Lightbox2</a> from Lokesh Dhakar, <a href="https://github.com/fancyapps/fancybox" rel="nofollow ugc">fancyBox3</a> from Jānis Skarnelis, <a href="https://github.com/jackmoore/colorbox" rel="nofollow ugc">Colorbox</a> from Jack Moore and <a href="https://github.com/miromannino/Justified-Gallery" rel="nofollow ugc">Justified Gallery</a> from Miro Mannino.

Fancyboxify vs Lightbox