GitHub Gist WordPress Plugin allows you to embed <a href="http://gist.github.com" rel="nofollow ugc">GitHub Gist</a> snippets with a [gist] tag, instead of copying and pasting HTML. For example, to embed the <a href="http://gist.github.com/447298.js?file=github_gist_wordpress_plugin_test.txt" rel="nofollow ugc">github_gist_wordpress_plugin_test.txt</a> file from <a href="http://gist.github.com/447298.js" rel="nofollow ugc">gist: 447298</a>, fill in the id and file attributes in the [gist] tag:
[gist id=447298 file=github_gist_wordpress_plugin_test.txt]
or
copy the embedding JavaScript code from GitHub and directly paste it in the body of the [gist] tag:
[gist]<code><script src="http://gist.github.com/447298.js?file=github_gist_wordpress_plugin_test.txt"></script></code>[/gist].
The [gist] tag also expands the content of the embedded Gist and wraps it with “<code><noscript><code><pre></code>” so that search engine spiders, users with javascript disabled and users reading your blog through RSS will still see your code in a blog entry.

GitHub Gist WordPress Plugin

GitHub Gist Wordpress Plugin allows you to embed GitHub Gist snippets with a [gist] tag, instead of copying and pasting HTML.

James Robinson

A simple plugin that enables a shortcode for embedding Gist code in WordPress.
The shortcode has two attributes, the Gist source URL and, optionally, the height of the embedded code window.
<pre><code>[gist src="" height=""]
</code></pre>
The Gist <code>src</code> attribute must be the embed URL, for example: https://gist.github.com/imaginarymedia/316a29936e5e7d709665.js
The Gist <code>height</code> attribute is optional and can be any value with a valid CSS unit measure: em, %, px, vh, etc. It will apply a max-height to the gist.
The plugin also creates UI buttons for both the visual and text editors.
If you have suggestions for improvements, please contact us. via the <a href="https://wordpress.org/support/plugin/wp-gist-embed" rel="ugc">plugin support page</a> and if you find this useful, please <a href="https://wordpress.org/support/view/plugin-reviews/wp-gist-embed" rel="ugc">review the plugin</a>.
Developed by <a href="https://jmr.codes" rel="nofollow ugc">James Robinson</a>.
** TO DO ** 
* Validate the gist src URL

WP Gist Embed

This plugin provides Gist embedding via shortcode as well as adding Gist embed buttons to the visual and text editors.

GitHub Gist WordPress Plugin vs WP Gist Embed