Planet P.E.A.C.E.

Planet P.E.A.C.E. is a location that once existed in the solar system, but was destroyed many years ago by Meta Knight Senior, who merely touched it to bring about its end. As Dark Matter is later revealed by Meta Knight Senior's Ghost to merely be Meta Knight Senior's Soul and consciousness after death possessing mindless monsters of Dynablaze's creation, it can be assumed this was one of the many planets he destroyed before becoming Dark Matter and continuing his reign as destroyer of worlds.

Planet P.E.A.C.E. is only mentioned in Meta Knight Story.