IconStore - Free icon packs by first-class designers
Flaticon - A database of free vector icons.
Feather Icons - Simply beautiful open source icons
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!
Iconjar - Store all your icons in one place, just a click away
IconArchive - Search through more than 735,000 free icons. Browse icons by category, artist, popularity, date. Organize and share your favorites.