Arda

Arda is the world of the Lord of the Rings continuum, also called Middle-Earth, intended to be a sort of pre-history Earth.

While many Sues try to claim this world as their home, Arda is often quickly dispatched of them with the help of the PPC.

Alumia
There was, however, one very noteable occasion where a Mary Sue, Alumia merged with the entire world. This required a mass exorcism with the help of every available Agent.