Oort Cloud & Kuiper Belt

Credit: Jedimaster
There are at least 100,000 icy and rocky objects in the Kuiper Belt, in fact some of the moons of Saturn and Neptune are thought to have originated there.
It's thought that the edge of the Oort Cloud marks the edge of our Solar System, though astronomers have yet to actually observe this part of the Solar System. We think that most of the comets in our Solar System come from here.