Arefly

Busy with setting every post’s first image to the Featured Image?
Use this plugin instead!
This plugin will auto set the first image of your post (for new posts only) to Featured Image.
If you do not want set the first image, you can still set your own Featured Image.
<h4>How Does It Work?</h4>
You do not need to set anything after you install and no any options.
The plugin will auto set the first image of your new posts to Featured Image.
<h4>How to exclude a specific post?</h4>
<ol>
<li>
Go in to the post/page you do not want to autoset Featured Image.
</li>
<li>
Find Meta Box name “Custom Field”.
</li>
<li>
Click “Enter new”.
</li>
<li>
Enter “no_featured_image” in Name Table and enter anything in Value Table.
</li>
</ol>

Autoset Featured Image

I can see how this would be useful, though, but for my purposes and by the name of it, I was hoping it'd go through old posts and, if they didn't have a featured image, set the first image.



Wish it worked for existing posts...

Auto Set the first image of your post to Featured Image.

Samuel Aguilera

NOTE: This plugin functionality is guaranteed by more than 10,000 active installs. But before installing this plugin bear in mind that its only purpose is to ADD the feature image ID to your post (in the same way that you would do using WP editor), it does not remove ANYTHING after deactivation. 
Before asking for support please read <a href="https://wordpress.org/plugins/easy-add-thumbnail/faq/" rel="ugc">FAQ</a> and <a href="https://wordpress.org/support/topic/please-read-before-posting-4" rel="ugc">this support thread</a>
<h4>How it works?</h4>
Checks if the post (any post type with thumbnail support, including pages) has already a featured image associated, and if not sets it using one of the following methods:
<ol>
<li>
Dynamically, for old published posts, the featured images are set only when needed to show them in the frontend. This means that the featured image is set (only first time) when a visitor loads the page where it needs to be shown.
</li>
<li>
For new content, the featured image is set in the publishing process.
</li>
</ol>
No options page to setup, simply install and activate.
If you want to exclude certain post type (e.g. pages), you can do it by using a filter. See <a href="https://wordpress.org/plugins/easy-add-thumbnail/faq/" rel="ugc">FAQ</a> for more details.
Easy Add Thumbnail doesn’t add any plugin data to your WordPress database. It simply adds the _thumbnail_id meta key with the ID of the attachment to be used as feature image (just the same that WordPress does when you set it manually).
Therefore it requires to have attached/uploaded at least one image to the post. If there’s not any image attached to the post, this plugin can’t help you.
Easy Add Thumbnail has not any control over how/when/where your featured image is displayed in your site, the display of the featured image in your site is TOTALLY controlled by your theme, this includes size, position, display it or not…
<h4>Requirements</h4>
<ul>
<li>WordPress 4.7 or higher.</li>
<li>PHP 5.6 or higher.</li>
</ul>

Easy Add Thumbnail

Automatically sets the featured image to the first image uploaded into the post (any post type with thumbnail support). So easy like that...

Autoset Featured Image vs Easy Add Thumbnail