Envato (formerly Eden) operates a group of eight online digital marketplaces that sell creative stock assets for web designers, including themes, graphics, video, audio, photography, and 3D models. It has over 1.5 million active buyers and sellers. Its highest-trafficked marketplace, ThemeForest, is the 204th most visited site in the world according to Alexa.
EnvatoMarket is where you can browse the marketplace.