The Nowhere
A plane of "existence" that is nothing and nowhere. When you are too lost for the Astral Plane, you find yourself in The Nowhere, from which nothing and no one ever returns, as far was anyone can prove, though sages theorize that a way can be found there. It appears as an infinite, eternal blank whiteness of non-existence, containing only objects and creatures who have become so lost they now don't exist anywhere else, or things which never existed. Located on this plane is Meinong's Jungle.
Among the native inhabitants are the Nowhales, known of because of their patronage of warlock.