Ruven

This plugin registers a custom post type for galleries and a taxonomy for categories.
Selected themes by Ruven provide templates to display galleries. 
In other themes you most likely have to add them by yourself.

Ruven Themes: Gallery

RT Gallery enables a "Gallery" post type and "Category" taxonomy.

Marcus Kober

You need more than one featured image for posts, pages and/or custom post types? Then this plugin is for you!
Enable multiple featured images for all post types (including custom post types and WooCommerce products) and show the images with a widget or the handy shortcode.
<h4>Features</h4>
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Add as many featured images as you need.
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Add the featured images to any post type (post, page or even custom post types and WooCommerce products).
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It is possible to use different featured images for different post types. Easily you can add two new featured images to pages and three to posts, if you need it that way.
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Fully customizable output – so it’s multilingual.
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Handy shortcode for displaying the featured images everywhere.
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Widget for displaying featured images in sidebars, etc.
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<h4>History</h4>
For one of my customers I had to assign two featured images to pages. One featured image was used as the header image and the other as a small button for the submenu. The images had to be different too (so I couldn’t simply use different images sizes) and so I wrote this little plugin.
<blockquote>
IMPORTANT NOTE TO THOSE UPDATING FROM 0.3: The Plugin comes with a new method for registering featured images and updates the post meta key. It is fully backwards compatible, but if you are calling the post metas directly then please update your code accordingly. The new format of the post meta key is kdmfi_YOUR_ID.
</blockquote>
<h4>Contribute</h4>
Feel free to ask if you have problems with this plugin. But please keep in mind, that this plugin is developed in the author’s spare time – so it may take some time to answer. 
Feature requests are welcome too!

Multiple Featured Images

I have been using this for years.  I can't even begin to count how many times I've been handed a design for a theme to build where the designer had a thumbnail for one gallery, then a totally different type of thumbnail for some other section of the site.  Nothing flashy here, just the perfect tool for the job.

This plugin makes adding extra featured image types a breeze.  It's a tool for developers, tho and not a simple plug-n-play solution. It doesn't simply add a second thumbnail to your posts, it does require some really lite code tinkering, so if you're not comfortable monkeying around in the functions file(s), this won't solve the problem for you.

A great tool for custom theme developers

Hi,

This is my first review, this plugin made me review it because it is so awesome.

Makes life easier. Thank you :)

Amazing plugin

Enables multiple featured images for all post types (including custom post types and WooCommerce products). Comes with a widget and a handy shortcode  …

Ruven Themes: Gallery vs Multiple Featured Images