Yith

Yith was one of several planets that Chris Cwej captured for his Superiors to use in the manufacture of their doppelganger worlds. (PROSE: The V Cwejes)

Behind the scenes
The planet Yith originates in the works of H. P. Lovecraft. It appears most prominently in The Shadow Out of Time, where it is inhabited by the Great Race of Yith, a civilisation of aliens that periodically escape apocalyptic events by projecting their consciousnesses across time and space and possessing the bodies of other species. The Great Race were later referenced in the P.R.O.B.E. audiobook Guardian At The Gate, but not explicitly named.