Grey Hole
From Tardis Wiki, the free Doctor Who reference
While Black holes are collapsing stars sucking everything in to a central point left by the collapse, and a White Hole is the opposite, “throwing all kinds of stuff out”, Grey Holes are something in between.
Grey Holes are extremely rare and should not exist in our Universe. When they do appear they can break down the boundaries between dimensions. As well as being rare they are incredibly dangerous. They exist in a constant state of flux, creating different levels of space-time distortions. Entire galaxies, untold solar systems can be contained in pocket universes. All of it is on the edge of oblivion. The guardians of the boundaries (the Boundary Nexus) are the Vorpon, Nexus Forms – the Grey Hole embodiments. (DWAM: The Grey Hole)
