Dæmos
From Tardis Wiki, the free Doctor Who reference
Dæmos Aka. Demos is the home planet roughly sixty thousand light years from Earth, on the far side of the Mutter's Spiral. The Dæmons were from this planet.
Dæmons were also said to either worship or dread The Beast. (DW: The Satan Pit)
Vorg and Shirna mention visiting a planet called Demos in episode two of "Carnival of Monsters", but it is unclear whether this is the same planet.