Stefano Lissa

Other Posts extract related posts for a given article and display them after its body.
One can choose the related post lists template between the ones packaged or create his own template 
directly on administration panel (very simple, just a bit of HTML).
Post images are extracted as well to create visually rich realted post list.
You may want to read the <a href="http://www.satollo.net/plugins/other-posts" rel="nofollow ugc">Other Posts Plugin Official Page</a>.

Marcel Pol

Benoit Chantre

Remco

A simple ‘related posts’ plugin that lets you select related posts manually. Supports any post types in WordPress, including custom ones.
Features:
<ul>
<li>Add related posts to your blog posts, pages etc.</li>
<li>Choose from posts, pages or custom post types.</li>
<li>Re-order related posts via drag and drop.</li>
<li>Lightweight in code and database-requests.</li>
<li>Includes Widget that shows the related posts.</li>
<li>List of posts can also be added to the content of your post.</li>
<li>Custom markup possible, build your own caroussel or anything you fancy.</li>
<li>Support for multilanguage plugins, like WPML and Qtranslate-X.</li>
<li>Duplicate plugin Related (Doubled Up) is included to build a second list.</li>
</ul>
The plugin was written to have the option to add related posts to each blog post using a simple but functional plugin. You can select the related posts yourself manually.
To display the related posts, there are three options:
<ul>
<li>You can use the widget that is included.</li>
<li>Use the content filter inside the settings.</li>
<li>Add PHP code to your template, see the installation docs.</li>
</ul>
For advanced options, see the installation docs.
<h4>Compatibility</h4>
This plugin is compatible with <a href="https://www.classicpress.net" rel="nofollow ugc">ClassicPress</a>.
<h4>Contributions</h4>
This plugin is also available in <a href="https://codeberg.org/cyclotouriste/related" rel="nofollow ugc">Codeberg</a>.

Manual Related Posts

Does exactly what is says it will. Very easy to integrate where you need it. Kudos to the dev who made it.

Simple and Easy to integrate

Very handy plugin for manually set your related posts !

Simple and Efficient

A simple 'related posts' plugin that lets you select related posts manually.

Other Posts vs Manual Related Posts