Far beyond the tiny planet of Azeroth, beyond the shattered shores of Outland -- or Draenor, as it was once called -- there lies the Great Dark Beyond. This dark, empty void between worlds exists even beyond the Twisting Nether. It is the space between planets, existing in the same material plane as the planets themselves. While the Twisting Nether exists within it, it should not be confused with the Nether, because they are two distinctly different entities.
Even now, the true battle between the forces of Light and Darkness approaches. We will all be called to join, and in the face of this conflict, all mortal suffering will be meaningless. -- Prophet Velen
In the existing universe of Warcraft, only a small handful of planets have been defined, floating somewhere out there in the vast, empty space of the Great Dark Beyond. All of these planets are connected, which gives way to a larger, slightly more tinfoil hat theory regarding the greater Warcraft cosmos and what it all means, when it comes down to it. But before we indulge in any speculation, we should define what lies within that Great Dark Beyond and how it all plays together in the vastness of the universe.