allilevine

This plugin adds an options page (Settings > Login Screen) that allows you to customize the WordPress Login Screen (wp-login.php). You can:
<ul>
<li>Upload a custom logo (it will be resized to fit if necessary)</li>
<li>Choose a link color</li>
<li>Choose a link rollover color (defaults to a darker shade of the link color)</li>
<li>Choose a button color (defaults to a button version of the link color)</li>
</ul>
The plugin also links the new logo to your site URL.

Simple Login Screen Customizer

Good

Choose a logo and link color for the login screen.  The plugin will do the rest.

Astahub

Haris

A fine designed and unique WordPress login page style that includes some customizations, also comes with login theme selector. Yaaaay!
Features :
<ul>
<li>Nice and well designed login style</li>
<li>Responsive design</li>
<li>Customizable login title</li>
<li>Customizable login logo</li>
<li>Customizable login message</li>
<li>Comes with 4 awesome login themes</li>
</ul>
Usage Instruction :
<ol>
<li>Install the plugin</li>
<li>Open the settings page on Appearance -> Login Screen</li>
<li>Change the plugin options then save it</li>
</ol>

Custom Login Screen

An unique and customizable WordPress login screen.

Simple Login Screen Customizer vs Custom Login Screen