This is the Browser of the MahApps.Metro.IconPacks
If you have no idea which icon you're supposed to take, then you can use the IconPacks Browser. You can search in every IconPacks and copy a raw Xaml code snippet to the clipboard.
The IconPacks library contains controls to use awesome icons from
Material
Font Awesome
GitHub Octicons
Modern
Entypo+
for WPF and UWP apps in a simple way.