IconStore - Free icon packs by first-class designers
Flaticon - A database of free vector icons.
Feather Icons - Simply beautiful open source icons
Icon Shop - Get beautiful premium quality vector icons
Iconjar - Store all your icons in one place, just a click away
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!