Earth Twenty-Three (post crisis) aka Pocket Universe

*A pocket reality created by the Time Trapper as part of an elaborate plan to destroy the Legion of Super-Heroes. The Trapper "pruned" his pocket reality until only Earth and Krypton had any life. Three Phantom Zone criminals destroyed all life on Earth, leaving the reality a dead wasteland with Matrix Supergirl being the only survivor.

Named in Crisis On Infinite Earths: Absolute Edition (November 2005)