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.

paulperkins

The Bimblers Exclude Posts plugin is used to exclude selected post categories from the main loop.
This might be useful if you use WordPress posts to author content which should not be listed on the front page, 
but you still want to utilise the features of a WordPress post type and do not want to go to the effort of 
setting up custom post types.
At this point in time, the post categories excluded by the plugin are hard-coded in the main class file. A future 
version of the plugin will include a configuration GUI.

Bimbler Exclude Posts

Excludes selected posts from the main loop. Filters by post category.

Categories but exclude vs Bimbler Exclude Posts