The Dune Universe - The Spaceships Guild

The spacing guild has this monopoly on interstellar travel in the dune universe. This monopoly is handled in a way that's different than a lot of real world monopolies, which are maintained by force or wealth. The power of the guild is such that if a great house chooses to surrender their planet in one of these squabbles and wars of assassins, they want to flee beyond the emperium. It almost mirrorso theological concepts.