Castrovalvan

Castrovalvans were the peaceful humanoid inhabitants of Castrovalva. Like their own city, they were created through Block Transfer Computation by the mathematical power of Adric's mind under the supervision of, who saw himself as the Castrovalvans' creator.

Nature
Physically, Castrovalvans were identical to humans, although they dressed in extravagant, often pastel-coloured clothing unlike any known human civilisation. Mentally, however, although they could pass for human, a close inspection would reveal their artificial, sketched-out nature: being part of the structure of Castrovalva, they were unable to grasp its idiosyncrasies and spatial paradoxes. Shardovan alone was intelligent enough to grasp that something about Castrovalva's space loop was illogical, and even then, only through "his philosophy"; his eyes still refused to actually see the paradoxical shortcuts.

However, contrary to 's belief, all the Castrovalvans possessed a degree of free will, and a fair few besides Shardovan had doubts about their true nature, even if they couldn't quite lay their fingers on it the way Shardovan had, as they confided in Shardovan himself during private conversations. When the Master revealed himself to them, they rebelled against him, holding him inside the rapidly-vanishing Castrovalva at the cost of their own lives so as to buy the Fifth Doctor and his companions time to escape. (TV: Castrovalva)

Government
The lengthy official history books of Castrovalva described the Castrovalvan people as having ascended, over twelve hundred years, from warring tribal people to a perfect, pacifist democracy.

The former part was pure fiction, as they had recently been created whole-cloth by the Master, but they were indeed a highly peaceful, refined society; each had their place and was content with their lot in life. They were governed by a magistrate known as the Portreeve, a wizened old man renowned for his wisdom and whom all loved and revered — although in truth the Portreeve was an avatar of their black-hearted creator. (TV: Castrovalva)

Culture
The Castrovalvans dressed in refined pastel-coloured garb (except for the librarian Shardovan, who wore black, and the Portreeve himself, who wore all white). Men wore cylindrical headpieces to go along with their robes, while women instead wore scarves over their heads, sometimes complemented with an aureola-like, translucent disk.

Although there were many books in the library, most notably the official History of Castrovalva, few ever read them but the Portreeve (who was, of course, their secret author), with even the librarian Shardovan claiming that he merely rearranged the books but did not read them, although in truth he had read through them and realised that they were forgeries, hence his keeping it quiet.

For sport, a ritual of hunting in garish feathered costumes was introduced; all Castrovalvan men but Shardovan took part in this ritual, which was claimed to be of the highest antiquity. Upon returning from the hunt (which took place just outside the walls of Castrovalva), the Castrovalvans would feast; (TV: Castrovalva) these feasts were common occurrences and so plentiful that the Portreeve, who was of weaker constitution, sought to avoid them for the sake of his digestive system. (PROSE: Castrovalva)

History
Castrovalva and its people were invented by (PROSE: Castrovalva) as part of a scheme to trap and defeat his long-time enemy, the Doctor, who had recently regenerated into a fifth, youthful body. He gave them a measure of reality by forcing boy genius Adric (trapped in a Hadron web by the renegade) to perform Block Transfer Computation.

The Castrovalvans existed long enough for Shardovan to progressively realise the truth about his world, before being visited by the Doctor and the two of his three companions who had not been captured, namely Tegan Jovanka and Nyssa of Traken. The Doctor eventually figured out the riddle of Castrovalva, leading the Master to reveal himself to gloat over his enemy in what he believed were the Doctor's final moments. However, he had failed to anticipate that the Doctor would be able to convince the witnessing Castrovalvans that the Portreeve had indeed betrayed them.

Although the Master was able to "unmake" any given rebellious Castrovalvan with a thought, as he demonstrated on Ruther the element of surprise was enough for one of the Castrovalvans to rush at the tapestry which embodied the Hadron web within Castrovalva and to destroy it.

As Castrovalva collapsed around them, the Doctor and his companions escaped through a breach in Castrovalva's reality which had formed by the cliffs as a result. The Master attempted to follow them, but the Castrovalvans, who had also followed the Doctor, chose to spend their last moments in existence helping the Doctor and friends make their getaway; they held the Master back, tearing at his clothes (TV: Castrovalva) and flesh (PROSE: Castrovalva) until the portal to the outside world closed and the city ceased to be, supposedly "gone forever" with its inhabitants.

Although initially hoping that this had also been the end of the Master, (TV: Castrovalva) the Doctor later discovered that he at least had somehow escaped the vanishing of Castrovalva. (TV: Time-Flight)