Doctor Who: 10 Alien Worlds That Need To Be Revisited

9. Marinus - The Keys of Marinus

The Keys of Marinus is the definition of a story that was incredibly large in scope but ultimately was let down by the production limitations of the program at the time. In terms of world-building on Doctor Who, Marinus is first class. It doesn't get a whole lot more ambitious or complex than what we see in this story. While most of the planets tend to give off the vibe that they're just one massive city with one predominant culture, The Keys of Marinus actually attempted to create a planet as rich and varied as our own. There are seas of acid, beaches of glass, and rubber-suited creatures called the Voord. But that's just the beginning -- there's also a city controlled by slugs in glass jars, snow-filled wastelands, and jungles with plants that have a tendency to fight back. Marinus didn't get a fair shake in the 60s, and now that the show actually has the budget to do the planet justice, Doctor Who kind of owes them another chance to get it right.