|Location:||Heart of the Horsehead Nebula|
|Status:||Closed, though briefly opened|
|Appearances:||The Hitch-Hiker's Guide to the Galaxy, Primary Phase, the original TV series|
Magrathea is an ancient planet located in orbit around the twin suns Soulianis and Rahm in the heart of the Horsehead Nebula.
It was the home a new form of specialist industry: custom-made, luxury planet building. Hyperspatial engineers sucked matter through white holes in space to form dream planets - gold planets, square planets, glass planets, platinum planets, soft rubber planets with lots of earthquakes - all lovingly made to meet the exacting standards that the Galaxy's richest men naturally came to expect.
It was the Magratheans who constructed the planet-sized computer named Earth (for a race of hyperintelligent pandimensional beings, the mice) to determine the ultimate question of Life, the Universe, and Everything, which is required to understand the Answer to Life, the Universe, and Everything.
Unfortunately, the venture was so successful that Magrathea soon became the richest planet of all time and the rest of the Galaxy was reduced to abject poverty. The Magratheans went into hibernation, awaiting an economic recovery that could afford their services once more.
Magrathea itself disappeared and its memory soon passed into the obscurity of legend.
In these enlightened days, of course, no one believes a word of it.
In The Hitchhiker's Guide to the Galaxy, the Heart of Gold and its occupants arrive at Magrathea with an Improbability-Field
generated sperm whale and bowl of petunias.
In And Another Thing, the planet Nano is built by the Magratheans.