Icons8 - Free app for Mac & Windows already containing 39,800 icons. Allows to search and import icons…
Iconscout - Design Resource Marketplace.
Control Illustrations - 108 free flat illustrations with customizable characters
Craftwork - A collection of User Interface resources made by Craftwork
Humaaans - Mix-&-match illustrations of humans with a design library.
3dicons - 3dicons library offers beautifully designed open-source 3D icons.