No-Space

Info:
No-Space was the dark form of every reality (which are different from parallel universes), Nightmare was one part of it (Reality Shift)

History:
No-Space was created when the first reality was made (light must have dark)

Nightmare (the dark form of Deram), fought with Deram, which, ultimately led to the first extinction of the Deramites

The Dreamer and The Rationalist fixed a rift from Eternal Space to No-Space

The Seventh Doctor stopped an attempt to release the creatures of No-Space onto Deram by the Veristis (A cult started on Deram's neighbor Thelis)

(Reality Shift)