Cheetah Planet

The Cheetah Planet (PROSE: First Frontier) was a mysterious sentient planet and the homeworld of the Cheetah People and Kitlings.

Astronomical data
Located outside of the Mutter's Spiral, (PROSE: Survival) the Cheetah Planet had a red-tinted sky, red sun, and peach-coloured moon. It had rough terrain, featuring rocks and sand. Due to the Cheetah People and Kitlings living there, it was covered in bones of dead humans and other creatures of the galaxy. There were also the ruins of an earlier civilisation. (TV: Survival) The magnetosphere was rich in artron energy, which is how it was able to metamorphose living matter. (PROSE: First Frontier)

The planet was in some sense, sentient and empathic, connected to the Cheetah People and when they fought in the Dead Valley, the planet became unstable and started to destroy itself.

"[T]he planet was alive: its rocks, its water and its trees all had an extra dimension. It was as if the fierce animals of the planet breathed the substance of the place and their blood pulsed with its rivers of lava. As they fought, the planet erupted; as they slept or watched its moons, the whole world grew stiller. Each was part of the other. It was the wild energy of the planet that gave the animals their savagery and the power to leap from world to world; it was the tug of the planet that brought them home again with whatever they had seized. But only the animals could leave and only the animals could return."

- Survival

The water on the planet had healing properties for the Cheetah People. The world allowed the Cheetah People to teleport to other planets to bring back prey. It also allowed people who wished to come home enough to return by teleportation. Humanoids such as humans and Gallifreyans slowly began to metamorphose, turning aggressive, causing them to fight with each other and they would physically begin changing into Cheetah People. described the world as dying because of its inhabitants' aggression. (TV: Survival)

Life forms
The Cheetah People were the dominant species, along with the Kitlings, who were used as part of their teleportation powers. They rode horses, although whether the horses were native to the planet was unknown. (TV: Survival)

History
At some point before the 20th century, a civilisation tried to conquer the planet. They bred the Kitlings to be their eyes and thought they could control the planet, but they were wrong. They too were turned into Cheetah People, leaving only the ruins scattered around the landscape. (TV: Survival) Having lost his Trakenite body temporarily, the Master considered options to extend his life, including the Cheetah Planet. (PROSE: The Quantum Archangel)

Around 1989, found himself on the Cheetah Planet after fleeing from the Antari system. He tried to escape by kidnapping humans from Earth, planning to use them to teleport himself to Earth. He finally did so with Midge and escaped to Earth. He was brought back to the Cheetah Planet with the Seventh Doctor. During a physical struggle between the Doctor and the Master, earthquakes shook the planet and the Cheetahs fled. The Doctor returned to Earth, leaving the Master behind, (TV: Survival) who escaped with a kitling named Shadow to Earth as the planet exploded, being hurled back 32 years to 1957. (PROSE: First Frontier)