Voltron, Defender of the Universe
The royal capital, whose name is not revealed, is the city where Castle Doom is located. A spaceport is also located there, and other royal government buildings are presumably located there as well.
Shadow Moon Canyon
(Seen and named in the episode Joyride to Doom).
It is unknown how far this laboratory is from Castle Doom. Haggar conducts magical research here, and it is likely the place where Robeasts are developed. Princess Romelle and Sven were part of a commando team that attacked the lab.
Politics and Government
The planet is ruled by a kingdom. The King serves as the head of state. Under the King serve Nobles who either hold ex officio positions in the royal government or govern fiefdoms on the planet. One episode shows Zarkon at least paying lip service to the idea that the Nobles' opinions are important. 
Under the command of the king, the military conducts combat operations. The Doom military has fleets of spacecraft, wings of combat and support aircraft, and armies. The mainstay of the kingdom's ground forces are Ultra Droids, which are effective force multipliers, as a squad of operators can effectively have the firepower of an entire company of flesh-and-blood troops.
In addition to conventional forces, Robeasts provide extra muscle.
- King Zarkon
- Prince Lotor
- Karp (Species unknown)
- Maahox (originally from Calum)
- Numerous Robeasts