Here are 10 free WordPress plugins that will add professional lightbox effect to the images in your posts and pages.
Responsive Lightbox allows users to view larger versions of images and galleries in a lightbox (overlay) effect optimized for mobile devices.
FooBox Image Lightbox
FooBox was the first lightbox to take responsive layout seriously. Not only does it scale images to look better on phones, but it rearranges it’s button controls to look great in both portrait or landscape orientation.
WP Lightbox 2
This plugin used to add the responsive lightbox (overlay) effect to the current page images and create photo albums/gallery on your WordPress blog.
Simple Lightbox is a very simple and customizable lightbox that is easy to add to your WordPress website.
WordPress Colorbox Lightbox
WP Colorbox plugin is a simple lightbox tool for WordPress. It allows users to pop up content in lightbox using the popular jQuery ColorBox library. They can also view the larger version of a particular media file without leaving the page.
WordPress plugin using the incredible fancyBox jquery lightbox.
Facebook Page Promoter Lightbox
Turn website visitors into Facebook fans. With this plugin you can display a Facebook Fan Page-Like Box inside a lightbox (overlay).
WP jQuery Lightbox
A drop-in replacement for Lightbox 2 and similar plugins, shedding the bulk of Prototype and Scriptaculous. Improved for mobile devices.
Social Gallery Lite
With Social Gallery your blog images are social, your visitors can use a familiar “facebook style” lightbox to view, like, comment & share your images. Social Gallery gets your blog more traffic and more engagement as well as offering a fantastic clean & poweful lightbox to boot.