text: Galactic empires are a science fiction setting trope, in which most or all of the habitable planets in the setting's galaxy are ruled by a single centralized political entity. Galactic empires most frequently appear in works in the sub-genres of science fantasy and space opera, although they may appear in other sub-genres as well. Works featuring galactic empires may have them as the story's focus, chronicling the empire's growth and/or decline. Alternatively, they may merely serve as a backdrop against which the events of the story play out.
  While depictions of galactic empires can vary wildly from work to work, most galactic empires share several key tropes:
  The empire, or at least its wealthier and more powerful regions, has advanced considerably in science and technology compared to current human civilization.
  Among these advances are some form of faster-than-light travel, which enables transit and communication across the empire's extent to occur in a reasonable time frame.
  Habitable worlds are either directly administered by representatives of the centralized imperial government, or else their local leadership is ultimately subordinate to the central government.
  Characterizations of these empires can vary wildly from work to work. They may be benevolent or malevolent; all-powerful or too weak or incompetent to exert power in anything but name; or anywhere in between.