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.

Kevin Sylvestre

This plugin uses the jquery implementation of fancybox and makes use of [attr] style selectors by adding a section to the wordpress header.
For more information and examples of slimbox visit:
<a href="http://fancy.klade.lv/" rel="nofollow ugc">FancyBox</a>

FancyBox

Loved it as a developer as it has nothing but a plain fancybox.



straight pulldown of fancbox

Enables fancybox on all image links including BMP, GIF, JPG, JPEG, and PNG links.

Fancyboxify vs FancyBox