Proteus 8 comes with hundreds of libraries. Common ones:
This article dives deep into everything you need to know about Proteus 8 libraries, including where to find them, how to install them, common errors, and how to create your own custom parts. Library For Proteus 8
Official and community sources:
Without the correct library, you cannot place, simulate, or route the component on a PCB. Proteus 8 comes with hundreds of libraries