Nicolas Notararigo

It’s not a simple plugin, it’s a complete style of Admin Panel in Dark Mode. 
This plugin transform your WP Admin in DarkMode. Install just plugin and activate it to see dark mode !

DarkPress

I like the concept (very nice if you manage different WP installations, you know where you are at a glimpse with admin schemes) and it’s efficient. But not perfect for the moment (I dont like the effect of pink buttons).

Dark site of Admin

It's a simple plugin to modify your WordPress admin interface in DarkMode

Hamid Reza Sepehr

Dark mode is a new trend on web design. Desktop apps like Adobe Softwares have already implemented dark mode into their UI, now this plugin adds dark mode/night mode feature into your WordPress installation. Dark mode/Night mode also helps. With version 1.1 now you can select button type, location and activated it on each page you want. Also save last time mode is added that save user choices for the last time. You can also define a period of time in which the dark mode would be automatically active on your website.
Note: 
The free version may have incompatibility with your theme. For a full featured version of the plugin alongside 24/7 technical support, please purchase the Premium version.
<h3>Credit</h3>
Here we thank everyone involved in production, testing and evolution of this plugin. Developers, third parties, online communities and buyers, we appreciate you all. 😎

Go Night Pro | WordPress Dark Mode Plugin

Go Night Pro Dark Mode/Night Mode WordPress Plugin enables dark mode or night mode with multiple options for your website.

DarkPress vs Go Night Pro | WordPress Dark Mode Plugin