Salostopus

Salostopus was a planet located in the constellation of Andromeda, home to an advanced humanoid race, some members of which practised polygamy. (TV: The Mysterious Planet) The humanoids lived in the planet's northern hemisphere, while the southern hemisphere was home to the Silostophans. (PROSE: Planet of the Elves)

History
In 2009, the Christmas Corporation enslaved some Silostophans to work in their factory on Salostopus. They were freed by the Fourth Doctor and Adric. (PROSE: Planet of the Elves)

At some point before 3999, Salostopus was attacked by the Wirrn. (PROSE: Placebo Effect)

Some of the inhabitants of the Faction Paradox Mission on Dronid were originally from Salostopus. (PROSE: Alien Bodies)

Circa 2000000, Sabalom Glitz was born on Salostophus (TV: The Mysterious Planet), as was Dibber (PROSE: Mission: Impractical).

Behind the scenes
The name of the planet is spelled "Salostopus" in all sources except for Placebo Effect and Mission: Impractical, in which it is spelled "Salostophus".