Ryan Welcher

This is a simple plugin that helps to clean up the admin side of WordPress by only showing the currently logged in user’s content the Post/Page/Media pages.
For the Media list, you can provide a list of user ID’s who’s Media will also be available to logged in users. It is highly recommended to create a user for this purpose.
Credits
This plugin was inspired by an article by <a href="http://premium.wpmudev.org/blog/author/pollyplummer/" rel="nofollow ugc">Sarah Gooding</a> on <a href="http://premium.wpmudev.org/blog/how-to-limit-the-wordpres-posts-screen-to-only-show-authors-their-own-posts/" rel="nofollow ugc">wpmudev</a> and uses portions of that code. Please see the source code for further details.

Restrict User Content

Limits Post/Pages/Media admin screens to only display the current user's content. Media can be shared by providing an ID list.

TrustedLogin

The easiest and safest way to restrict access to your WordPress site’s Dashboard and administrative menus. Remove Dashboard Access is a lightweight plugin that automatically redirects users who shouldn’t have access to the Dashboard to a custom URL of your choosing. Redirects can also be configured on a per-role/per-capability basis, allowing you to keep certain users out of the Dashboard, while retaining access for others.
<ul>
<li>Limit Dashboard access to user roles:
<ul>
<li>Admins only</li>
<li>Admins + editors</li>
<li>Admins, editors, and authors</li>
<li>or restrict by specific user capability</li>
</ul>
</li>
<li>Choose your own redirect URL</li>
<li>Optionally allow users to edit their profiles</li>
<li>Display a message on the login screen so users know why they’re being redirected</li>
</ul>
Blocking access to the Dashboard is a great way to prevent clients from breaking their sites, prevent users from seeing things they shouldn’t, and to keep your site’s backend more secure.
Allow only users with roles or capabilities:
You can restrict Dashboard access to Admins only, Editors or above, Authors or above, or by selecting a specific user capability.
Grant access to user profiles:
Optionally allow all users the ability to edit their profiles in the Dashboard. Users lacking the chosen capability won’t be able to access any other sections of the Dashboard.
Show a custom login message:
<ul>
<li>Supply a message to display on the login screen. Leaving this blank disables the message.</li>
</ul>

Remove Dashboard Access

This plugin is a must-have when working with public roles.

A must-have!

Disable Dashboard access for users of a specific role or capability. Disallowed users are redirected to a chosen URL. Get set up in seconds.

Restrict User Content vs Remove Dashboard Access