UI Faces - Avatars for design mockups
3dicons - 3dicons library offers beautifully designed open-source 3D icons.
Nucleus UI - Free UI component library to create mockups in Figma quickly
Wannathis - 3d illustrations and freebies
lstore.graphic - Mockup Scene Creator
IconShock - Over 2 million free icons in 400+ icon sets over 30 styles