Ouch! Illustrations by Icons8 - Professional, perfectly matching, and customizable illustrations for any designs
Android Nougat GUI - Free fully customizable Android UI Kit for Sketch
Control Illustrations - 108 free flat illustrations with customizable characters
Contra Wireframe Kit - Open source wireframe kit for design and prototyping 🚀
Humaaans - Mix-&-match illustrations of humans with a design library.
Epic Pxls - UI kits, icons, templates, mockups and more, free