Darshan Sawardekar

This plugin adds an <code>[xkcd]</code> shortcode tag to WordPress. You can use it to embed the <a href="http://xkcd.com" rel="nofollow ugc">XKCD</a> webcomic into your posts and pages.
It takes a <code>num</code> attribute that specifies the number of the XKCD comic to embed. For Eg:- To embed the 100th comic use,
<pre><code> [xkcd num='100'] </code></pre>
When the <code>num</code> attribute is omitted the latest XKCD comic is shown instead.
<pre><code> [xkcd] </code></pre>

xkcd-shortcode

Adds an [xkcd] shortcode that loads the XKCD webcomic by number.

Dan Griffiths

Allows display of XKCD comics through a simple widget or shortcode. Both can be configured to display the latest comic, a random comic, or a specific comic.
For example, to display comic 100 using the shortcode, simply put the shortcode [xkcd id=”100″] where you want it to be shown.
[xkcd id=”random” title=”false”] will display a random comic, without the title.

XKCD Embed

A simple plugin to display XKCD comics on your website.

xkcd-shortcode vs XKCD Embed