Mark Jaquith

This plugin allows you to customize the logo on the WordPress login screen. There is zero configuration. You just drop the logo file into your WordPress content directory, named <code>login-logo.png</code> and this plugin takes over.
Note that you should use a transparent background on the PNG image, crop it tightly (no padding pixels) and use a width of exactly 312 pixels for best results. Wider images will be downscaled in modern browsers, but it isn’t recommended to rely on that.
This plugin also works in the <code>mu-plugins</code> directory.

Login Logo

Customize the logo on the WP login screen by simply dropping a file named login-logo.png into your WP content directory. CSS is automatic!

Nazmul Hossain Nihal

Using this plugin you can make changes on login screen of your WordPress site.It can detect your logo image size automatically.You can add logo to your login screen,change the color of the other elements of login page.It has a color picker so you don’t need to worry about color codes.
What you can do with this :
<ul>
<li>Change Login Logo</li>
<li>Add Favicon of login page</li>
<li>Change Logo Hover Text</li>
<li>Change Logo Url</li>
<li>Change Background Color</li>
<li>Change Login Form Background Color</li>
<li>Change Label Color</li>
<li>Change Input Text Color</li>
<li>Change Input Background Color</li>
<li>Add Custom CSS</li>
<li>Use Shortcodes</li>
</ul>

Login Screen Manager

Using Login Screen Manager in your Wordpress site you can easily customize your login screen.You can add your own logo to the login screen,change styl …

Login Logo vs Login Screen Manager