Parallel Sect

The Parallel Sect was an organisation known to have possessed a dimensional nexus. The Parallel Sect could easily travel through parallel universes, and the Sixth Doctor compared their skill at travelling through these universes to "the same way people cross the street." The Parallel sect were known in the myths and legends of millions of races throughout the cosmos, including that of the Time Lords.

The Valeyard attempted to use this nexus to restore himself, only for the Master to arrive seeking to use it for his own purposes. (AUDIO: The End of the Line)