Hyspero was a planet at the very edge of the universe, in the area of space known as the Penumbra of the Galaxy's Ultimate Portion. (PROSE: Enter Wildthyme) The planet was ruled by the Scarlet Empresses, a dynasty of powerful beings who preserved themselves in jars. (PROSE: The Scarlet Empress, Enter Wildthyme)
Hyspero was one of the few places in N-Space where magic was commonplace. (PROSE: The Blue Angel) It was also one of the only places in the universe from which the Obverse could be reached. (PROSE: Enter Wildthyme)
Hyspero was a geographically diverse world, featuring a range of biomes such as desert, mountain ranges, jungle, forest, arctic wilderness, and ocean. However, the planet was also an impossible series of "levels," connected and accessible to each other with gateways and lifts. Hyspero's desert, Hyspero Central, the mountains, the town of Fortalice, Old Lady Flower's indoor jungle, connecting underground river, and the Forest of Kestheven were all on the same outer level of planet. Beneath this level existed an arctic area and one of Hyspero's oceans.
According to Gila, not all the levels even had gateways or lifts, leaving people wishing to work further down the planet to jump. According to the Eighth Doctor and Sam, the lifts inside the gateways looked mundane, like something at department stores. (PROSE: The Scarlet Empress)
Before the rule of the Scarlet Empresses, Hyspero was a primitive world covered completely in desert. A hawk-like alien species came to Hyspero and claimed the planet as part of their empire. After sculpting the planet into a slightly more hospitable dream world, the aliens left behind one of their own to rule Hyspero: the first Scarlet Empress. (PROSE: The Scarlet Empress) Some accounts indicate the first Empress was Euphemia, (PROSE: Enter Wildthyme, Wildthyme Beyond!) while one account indicates Cassandra was the first to hold the role. (PROSE: The Scarlet Empress)
The Hysperons worshiped the first Empress and built her the Scarlet Palace. Hyspero became a popular tourist destination. During her reign, the first Empress introduced the tradition of tattooing the Scarlet Guard. (PROSE: The Scarlet Empress) A hundred years after her rule began, the Empress was betrayed and sealed in a glass jar which was kept in the catacombs beneath the Scarlet Palace. (PROSE: Enter Wildthyme)
One of the Scarlet Empress' daughters took her place on the throne; she too was eventually sealed in a jar and stored beneath the palace. This pattern continued for many generations, with the Palace catacombs filling up with many preserved monarchs. (PROSE: The Scarlet Empress)
After Iris Wildthyme left the Obverse, the Clockworks followed her out of that universe to Hyspero. Unable to find her, they waited millennia there for her to return to the planet. (PROSE: Wildthyme Beyond!)
The Four and the theft of the first Empress
Tens of thousands of years after the original Scarlet Empress, (PROSE: Enter Wildthyme) there came to be an Empress who did everything in her power to remain on the throne. Unlike her predecessors, the Empress continued to rule Hyspero after she was preserved in a jar.
Around this time, the Four had many adventures across Hyspero. The Empress frequently hired them to complete tasks for her. Among their various adventures, the Four stopped Sit al-Husn from taking over Hyspero with his cyborg army, destroyed a Dalek scout ship which landed on Hyspero, and assassinated the Empress' rivals. When the Empress asked the Four to assassinate her own daughter Julia, the Four disbanded due to a conflict over whether to follow through on the Empress' orders.
In the second decade of the Abbasid Era, the first Scarlet Empress was stolen from the Scarlet Palace catacombs. According to one account, Angela stole the Empress and took her to a manor in the Forest of Kestheven. (PROSE: The Scarlet Empress) According to another account, Terrance infiltrated the palace disguised as a vizier and stole the Empress, putting her onto the Begins at Home. (PROSE: Enter Wildthyme)
Reunification of the Four
Needs more information from The Scarlet Empress.
Other visits to Hyspero
A hole in the Very Fabric of Time and Space in the bookshop Chimera led to Hyspero. Reginald Tyler, Henry Cleavis, and Catriona Mackay visited a Hysperon marketplace through this hole in reality. (PROSE: Fellowship of Ink)
Hyspero as fiction
The final episode of The Iris Wildthyme Show ended with the main characters being stuck on Hyspero. It wasn't until 2011 that this storyline was concluded in the tie-in novel Iris Wildthyme Returns to Hyspero. (PROSE: Wildthyme Beyond!)