Vincent Dubroeucq

Visit your blog posts listing page, or a single post page, and open up the WordPress customizer.
Under Tiny Thumbnail Settings, choose or upload your default image. That’s it !
Enjoy !

Tiny Default Thumbnail

Allows you to add a default featured image to posts. Just add a default image in your customizer settings !

zggz

If your theme makes thumbnail pictures links (which casuses a useless refresh on click), 
use this plugin to disable that. That’s it. Once enabled, it will make every featured image 
(on a post/page) unclickable.
<h3>Contributing</h3>
If you have any requests, bugs, or improvements, leave them at the GitHub for this plugin 
<a href="https://github.com/zggz/unclickable-featured-image" title="GitHub Repository" rel="nofollow ugc">GitHub repo link</a>

Unclickable Featured Image

A WordPress plugin that forces all featured images to NOT be links

Tiny Default Thumbnail vs Unclickable Featured Image