Icons8 - Free app for Mac & Windows already containing 39,800 icons. Allows to search and import icons…
Craftwork - A collection of User Interface resources made by Craftwork
Iconscout - Design Resource Marketplace.
3dicons - 3dicons library offers beautifully designed open-source 3D icons.
IconShock - Over 2 million free icons in 400+ icon sets over 30 styles
Humaaans - Mix-&-match illustrations of humans with a design library.