PoseLab

A simple plugin that displays a list of all categories except those selected in widget preferences. Unlike other similar plugins like “Almost All Categories Widget”, Categories but exclude uses the latest version of WordPress Widget API, which is multi-widget, which lets you use the wigdet more than once. Mostly, I created the plugin to use it with the plugin “WPML” along with “Widget Logic” to use the same widget for each language.
This will allow you to create a custom category list which will show the categories you want, and will hide the categories you do not want. For example, say you have a particular category you don’t want to be displayed named “Announcements”. You can use this plugin to display all of your other categories, except the category “Announcements”. You are not limited to just excluding one category; you can exclude multiple categories.
Languages:
<ul>
<li>Spanish (es_ES) – <a href="http://poselab.com/" rel="nofollow ugc">PoseLab</a></li>
<li>French (fr_FR) – <a href="http://www.tradpress.fr/" rel="nofollow ugc">TradPress</a></li>
</ul>
If you have created your own language pack, or have an update of an existing one, you can <a href="mailto:javierpose@gmail.com" rel="nofollow ugc">send me</a> your gettext PO and MO so that I can bundle it into the Categories but exclude. You can download the latest POT file <a href="https://plugins.trac.wordpress.org/browser/categories-but-exclude-widget/trunk/categories-but-exclude.pot" rel="nofollow ugc">from here</a>.

Categories but exclude

Displays all categories except those selected in widget preferences.

Michael Adams (mdawaffe)

Just One Category will cause WordPress to display on a category archive page 
only those posts which are direct members of that category, i.e. this plugin 
will exclude from that category page all posts which belong to any of that 
category’s subcategories but do not belong to the category itself.

Just One Category

On a category's archive page, displays only the posts directly in that category, not in any sub-categories.

Categories but exclude vs Just One Category