Font Awesome - Font Awesome makes it easy to add vector icons and social logos to your website. And version 5 is redesigned and built from the ground up!
Zwicon - A simple, carefully designed collection of icons
1000 Detailed Creative Icons - Carefully designed icons with tons of fine details
Streamline icons - The world’s largest icon pack library - 100k icons and illustrations.
Icons Mind - The Biggest iOS 8, iOS 7 & Android Icons Pack
Vivid JS - A highly customizable, open source SVG icons library