Vicons Design - Vector & Design Consultancy
IconArchive - Search through more than 735,000 free icons. Browse icons by category, artist, popularity, date. Organize and share your favorites.
Flaticon - A database of free vector icons.
Game-Icons - Huge collection of free icons for games and apps.
Iconscout - Design Resource Marketplace.
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!