Galactic Empire
Established in 19 BBY by Supreme Chancellor Palpatine -- who formally dissolved the Old Republic to thunderous applause in the Galactic Senate and assumed the new title of Emperor -- the Galactic Empire is the dominant political entity in the Star Wars galaxy.
Organization
The Galactic Empire is a military dictatorship established when Chancellor Palpatine declared himself Emperor. Following the Emperor's dissolution of the Senate, all power in the Empire flows directly from him. Regional governors manage territories within the Empire on the Emperor's behalf. The Empire's military forces -- particularly its Stormtroopers -- are personally loyal to the Emperor himself.
Attributes
The Empire incorporates a diverse array of species and cultures, but humans hold all positions of importance under Palpatine's reign. Imperial technology is essentially stagnant, but they already possess technology enabling real-time interstellar communications, trans-galactic travel in a matter of hours, advanced weapons, shields capable of protecting entire planets, and obscene power resources. The most notable innovation during Palpatine's reign is the Death Star, an unprecedented up-scaling of turbolaser technology capable of obliterating an entire planet in an instant.
A small minority of sentient beings in the Empire are able to manipulate an energy field called the Force, enabling them to perform an array of paranormal feats such as telekinesis, telepathy, clairvoyance, and precognition with varying levels of ability.
Territory
The Empire controls virtually the entire galaxy, including worlds like Tatooine, where the Empire's predecessor, the Galactic Republic, had no influence.
Threat Assessment
The Empire is an enormous threat to other civilizations. To prevent unrest, the nature of the totalitarian police state requires an external threat to justify its massive military expenditures. The Empire is threatened from within, however, by the Rebel Alliance, an insurgent group dedicated to the overthrow of Palpatine and restoration of a representative government.