Callis (Castle Hydra)

Callis was a temporal scientist. She wanted to know why there were many copies of themselves in the vicinity of the castle. She kept herself masked when in their presence to save their sequence. She asked the Fifth Doctor for help in her work. (AUDIO: Castle Hydra)

The Doctor would eventually discover that Callis, along with many other people throughout history who looked like her, were caused by a group of Time War Daleks who — while on a mission to prevent the rise of Time Lord society on Gallifrey — created a time distortion which created alternate versions of themselves as four un-mutated Kaled people. This time distortion also caused multiple copies of these four Kaleds to appear at various points throughout time and space. (AUDIO: Effect and Cause)