glowrocks

For posts and pages with no featured image, and no images associated with the entry, a random image is selected from the media library and set as the featured image.
The plugin currently does not test for images associated with the entry.
Instead, install and run the Easy Add Thumbnail plugin (https://wordpress.org/plugins/easy-add-thumbnail/).
That plugin will set the featured image on all entries that both have no featured image AND have an image associated with the post.
What is left is entries without featured images and without any images.
This plugin provides a random image from the sites media library so that index pages look more interesting (and possibly confusing/humorous depending on which image is randomly selected.)
There is a notice at the bottom of each post the plugin has updated noting the random image. In a future release, this note will be optional via the standard user interface, but for now one has to edit the plugin and remove the last “filter” line. This notice is not displayed if the plugin is removed.

Random Auto Featured Image

For posts/pages with no featured image, & no images associated with the entry, a random image is selected from media library & set as featured image.

Daiv Mowbray

Take control your photos and image display. Add an attached image/images or randomly selected image to any post without an image. Provides a shortcode for inserting an attached image or featured image into your post. Provides an easy way to change image properties globally. At the click of a button all post size images can be changed from thumbnail size image to medium size image or any available image size. Changing any default option in the admin/settings/superslider-image page will change that property for all photos or images inserted with the [image] shortcode.
Features
<ul>
<li>Provides the shortcode [image] to insert an image into your posts / page.</li>
<li>Automatically inserts the shortcode [image] into your posts / page.</li>
<li>Checks for attached image, then featured image then if none is found it shows a random image.</li>
<li>Inserts a randomly selected image into any post without an image attached.</li>
<li>Option to display a different image each time a post is viewed 
This allows you to set a default image code setup. Avoids the hard coded 
image in your post. Each inserted [image] shortcode can be customized with 
properties which stay fixed. Changing a default option in the 
admin/settings/superslider-image page will change that property for all images 
inserted with the [image] shortcode. This works for one or more images attached 
to this post, or any image id from your media library. ie: [image image_id=”129″] 
where 129 is the image id available in your media manager list.</li>
</ul>
Demos
See screen shot of admin panel. This plugin can be seen in use here:
<ul>
<li><a href="http://superslider.daivmowbray.com/2010/superslider-image-demo-1" title="Demo 1" rel="nofollow ugc">Demo 1</a></li>
</ul>
Support
If you have any problems or suggestions regarding this plugin <a href="https://wordpress.org/support/plugin/superslider-image" title="support forum" rel="ugc">please speak up</a>
Other Plugins 
Download These SuperSlider Plugins here:
<ul>
<li><a href="https://wordpress.org/extend/plugins/superslider/" title="SuperSlider" rel="ugc">SuperSlider</a></li>
<li><a href="https://wordpress.org/extend/plugins/superslider-postsincat/" title="Superslider-PostsinCat" rel="ugc">Superslider-PostsinCat</a></li>
<li><a href="https://wordpress.org/extend/plugins/superslider-show/" title="SuperSlider-Show" rel="ugc">SuperSlider-Show</a></li>
<li><a href="https://wordpress.org/extend/plugins/superslider-login/" title="SuperSlider-Login" rel="ugc">SuperSlider-Login</a></li>
</ul>
NOTICE
<ul>
<li>The downloaded folder’s name should be superslider-image</li>
</ul>
<h3>USAGE</h3>
If you are not sure how this plugin works you may want to read the following.
<ul>
<li>Example shortcode to over ride global options: [image size=”thumbnail” image_link=”on” link_type=”large” image_caption=”on” lightbox=”on” limit=”1″ align=”right” image_frame=”on” image_id=”159″]</li>
</ul>
<h3>OPTIONS AND CONFIGURATIONS</h3>
<pre><code>* 'order' = 'ASC', 
* 'orderby' = 'menu_order',
* 'size' = "medium",
* 'image_link' = "on",
* 'link_type' = "large",
* 'caption' = "on",
* 'lightbox'= "on",
* 'limit'= "1",
* 'random'= "on",
* 'align'= 'center',
* 'image_frame'= 'on',
* 'image_id'= '234',
* 'add_text_editor'= 'on'<h3>To Do</h3>
</code></pre>
* Open to suggestions
<h3>Report Bugs Request / Options / Functions</h3>
<ul>
<li>Please use the support system at the WordPress.org support forums</li>
</ul>

SuperSlider-Image

Take control your photos and image display. Add an attached image/images or randomly selected image to any post without an image.

Random Auto Featured Image vs SuperSlider-Image