Galactic Empire

The Galactic Empire was one of the main factions in the universe of Star Wars. It was a galaxy-spanning regime established by the series' lead villain, Palpatine, to replace the Galactic Republic. The Galactic Empire was first introduced in A New Hope and the Imperials are the main antagonists of the original trilogy and Star Wars Rebels.

Government and politics
The Empire was ruled with absolute power by Emperor Palpatine, with Mas Amedda as Grand Vizier, and Darth Vader as Supreme Commander of all Imperial Forces. Imperial rule was authoritarian. There was little to no freedom of speech and dissidents were punished harshly. According to the introduction to the official field manual for the Empire's military forces, this was because the Empire aimed and celebrated one ruler, code of law, common tongue, and education in social progress, and wanted to ensure unity.

The Galactic Empire was actually more decentralized than the Galactic Republic. Systems were grouped in sectors and sectors in turn into oversectors. These were controlled by the Moffs and Grand Moffs, who exercised power in the disparate regions of the galaxy. This was in contrast to the structure of the Galactic Republic, which placed senators in control of their respective sectors. The planets of the Empire were no longer given a say in the government, but were now kept in line through fear of force.

Amongst high-ranking military personnel, the Emperor's name was spoken with fear along with his former Sith apprentice, Darth Vader. Though frequently styled as a "Lord", and treated with a similar fearful deference as Palpatine, it is unclear whether Vader performed an official function of government. Serving the Empire and its interests were numerous Dark Side Adepts, Force-sensitive individuals of the Inquisitorius trained to track down and eliminate any surviving Jedi. Due to the nature of their mission, Inquisitors could commandeer local Imperial forces, and possessed authority over other officers in the Imperial military. The highest ranking officers in the Navy were the Grand Admirals, who outranked even Grand Moffs. They controlled entire fleets and were second only to the Emperor on the military's chain of command. One such Grand Admiral was Thrawn, who was tasked with defeating the Rebel Alliance.

Imperial Senate
The Imperial Senate was the de jure legislative council of the first Galactic Empire. It was the successor to the Galactic Senate of the Republic, which was reformed into an autocratic regime when then Supreme Chancellor Sheev Palpatine declared himself Emperor.

After the end of the Clone Wars - which was carefully masterminded by the Dark Lord of the Sith known as Darth Sidious - Sidious abandoned his public persona of Palpatine, the Supreme Chancellor of the Galactic Republic and chairman of its senate. He ordered a special session of Congress and proclaimed himself Galactic Emperor, turning the old Republic into a New Order in his image. The representatives overwhelmingly supported the announcement, except for a few delegates, including Padmé Amidala and Bail Organa. In the wake of the regime change, the Galactic Senate became the Imperial Senate.

Most members of the Imperial Senate secretly supported the Rebel Alliance, as they correctly saw Palpatine as nothing more than a tyrant, Palpatine, unknown to the public, intended to disband the Senate permanently, but he waited until the Death Star was completed. As of A New Hope, Palpatine dissolved the Imperial Senate permanently.

Military Forces
Unlike the military forces of the Republic, it served as Palpatine's enforces to enforce his tyrannical rule, this eventually resulted in the founding of the Rebel Alliance, to free people of the galaxy from Palpatine's oppression. This resulted in the Galactic Civil War that would last for nine long years, out arrogance Palpatine did not take the Rebel Alliance very seriously, due to the fact that they only a few Force-users in their group; like Ahsoka Tano, Kanan Jarrus, Ezra Bridger, and Luke Skywalker, this would eventually lead to the Galactic Empire's downfall.

The Imperial Navy originated from the Galactic Republic's naval branch and came to have its ships patrol the vast majority of Imperial space throughout the reign of Emperor Palpatine's New Order. Consisting mainly of Star Destroyers and TIE Fighters, the Imperial Navy was tasked with maintaining order in the galaxy.

History
The Galactic Empire's origins are explained in Revenge of the Sith, where it replaces the Galactic Republic in the midst of a galactic civil war orchestrated by Palpatine, then the Republic's Supreme Chancellor. Palpatine is also secretly the Sith Master/Dark Lord of the Sith, Darth Sidious who intends to purge the Jedi Order and restore the Sith Order to power in the galaxy. Palpatine's Sith identity is only known by a small few throughout his life. Palpatine claims that the Jedi attempted to assassinate him and overthrow the Galactic Senate and declares the Jedi to have committed treason. Palpatine declares that the civil war with the Separatists in combination with the Jedi coup d'état require the reorganization of the Republic into a state that can provide stability, and a safe and secure society, a Galactic Empire with himself as Emperor. The Senate that he has manipulated overwhelmingly applauds Palpatine's decision.

Emperor Palpatine proceeds to purge the Jedi, who had been the upholders of peace and justice in the Old Republic, and replaces them by redeeming the Sith. Though Palpatine's Sith identity remains a secret to most, his apprentice Darth Vader is the Sith Lord who is publicly known to the galaxy as the ally of Palpatine who is serving the Empire to purge the Galaxy of the Jedi. Vader is the ruthless second-in-command of Palpatine who is feared by many in the galaxy. By the time of the events of A New Hope, the Empire has transformed into a fully authoritarian regime, with opposition in the form of the Rebel Alliance.

The Galactic Empire is described in various Star Wars media as a brutal dictatorship, one based on "tyranny, hatred of non-humans, brutal and lethal force, and, above all else, constant fear".