Asteroid (The Wishing Beast)

From Tardis Wiki, the free Doctor Who reference

A small skull-shaped asteroid in the distant past was home to the Wishing Beast. The Beast could reshape the surface of the asteroid using its mental powers; at times the asteroid was covered by a forest with a large mansion in the middle, at other times it was barren rock which emanated deadly radiation. (AUDIO: The Wishing Beast) It was in a remote location, (AUDIO: The Vanity Box) in a different galaxy than that of Earth. (AUDIO: The Wishing Beast)

The Sixth Doctor sent the Beast to the asteroid through a tear in the Very Fabric of Time and Space. (AUDIO: The Vanity Box)

The three Applewhite siblings - Maria, Eliza, and Daniel - became stranded on the asteroid while fleeing a space war. They discovered the Wishing Beast and were mutated by it; the sisters were given telekinetic powers by which they could trap travellers on the asteroid and Daniel was fused with the Beast to create a golden dragon. Over the course of 300 years, hundreds of travellers came to the asteroid and had their souls eaten by the dragon. The forest of the asteroid became teeming with the ghosts of the Beast's victims.

The Sixth Doctor and Melanie Bush were lured to the asteroid by a distress signal Applewhite sisters. Unaware of the Doctor's long lifespan, the sisters tried to feed Mel's soul to the Beast. The Doctor learned of the sisters' true nature from the ghosts of the forest and sacrificed himself to the Beast. In the Beast's stomach, the Doctor met Daniel and motivated him to overthrow the influence of the Beast. Daniel unfused himself from the Beast, rendering it a powerless box. Without the Beast's influence, the asteroid began reverting to a lifeless rock. The Doctor and Mel escaped in the Doctor's TARDIS before the oxygen disappeared. (AUDIO: The Wishing Beast)