The Moroks are a hostile humanoid species which has invaded the peaceful planet Xeros and exterminated the population, sparing only the children and turning the survivors into an enslaved race. The planet was converted into a huge museum in which the Moroks exposed relics from their enemies. In some cases, their enemies themselves were preserved as expositions for the macabre museum. The expositions reveal that the Moroks have been victorious even against Daleks, illustrating their formidable military power.
At some point, however, the Morok Empire fell into stagnation and decline. The Xerons, assisted by the Doctor's companion Vicki Pallister, managed to revolt against their masters and reclaim their planet.
- Doctor Who, season 2 (First Doctor) - The Space Museum (1965)