CGTrader - CGTrader is an online marketplace at which artists can sell and buy Revit and 3D models.
Textures.com - Textures.com is a website that offers digital pictures of all sorts of materials.
3DOcean - 3D Models & Accessories From $1 for 3D Models, Textures, Materials & Shaders, 2D Concepts...
Poly Haven - Poly Haven (formerly known as Texture Haven) is an online website where you will find scanned textures without any cost and that are of high quality.
3DExport - 3DExport is a 3D model marketplace where you can buy and sell 3D models, CG textures and digital objects for 3D printing with royalty free. Professional 3D models - 3DExport.com
Poliigon - A library of materials, and HDR's for artists including free textures that want photorealism.