Tranons

A simplistic plugin that allows for the furthur customization of your category list. 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. Essentially, this plugin provides more functionality to your category list.

Category Excluder Widget

This widget allows you to easily create a specific category list. You can exclude any categories you please.

zugrina

Small plugin that allows you to exclude pages or posts from WordPress administration post/page listing. It also works with custom post types. Pages or posts can be excluded per user role.
One good example would be a login page with a shortcode for login form. You want to make sure that this page is not deleted by accident.

Tailored Easy Exclude

Small plugin that allows you to exclude pages or posts from WordPress administration post/page listing, and post/page can be excluded per user role.

Category Excluder Widget vs Tailored Easy Exclude