Vorpon
From Tardis Wiki, the free Doctor Who reference
The Vorpons were the Guardians of the Boundary Nexus, in a Grey Hole and formed of the Grey Hole itself (“Nexus Forms”). They were an expression of the Grey Hole’s intelligence. The threat that the Vorpons posed to those who intruded in the Grey Hole was to have their timeline immobilised if the threshold was crossed. Had the Vorpons threat been carried out then the intruders would have become trapped in the Grey Hole when the Boundary Nexus was closed, but that would mean that the guardian Vorpons would also cease to exist. (DWAM: The Grey Hole)
