Galactic empires are a fairly common theme in science fiction. The idea suffers from practical difficulties, not least that it requires faster-than-light travel (and communication) to hold the empire together. Nonetheless, many authors have either used a galactic empire as background, or written about the growth or decline of such an empire. Some of these empires are clearly based on the Roman empire; the Galactic Empire of Isaac Asimov's Foundation series (which inspired empires of later writers and film-makers) being an obvious example. The best known to the general public today is probably the empire from Star Wars, which was formed from the ashes of the Galactic Republic.
