The Galactic Empire, also known simply as the Empire, is a fictional autocracy featured in the Star Wars franchise. Introduced in the 1977 film Star Wars, it is the main antagonistic faction of the original trilogy, which also includes The Empire Strikes Back (1980) and Return of the Jedi (1983). An oppressive dictatorship with a complicated bureaucracy, the Galactic Empire seeks the rule and social control of every planet and civilization within the galaxy, based on anthropocentrism, nationalisation, state terrorism, power projection, and threat of lethal force.

The Galactic Empire's rise was not a violent takeover by force, but rather a consolidating unprecedented and unchecked power in the Chancellor via a calculated Gleichschaltung-like dismantling of the galaxy's most powerful institutions by undermining the public's faith in these institutions, rewriting constitutional foundations, controlling the Jedi Council, weakening the Galactic Senate, court packing the Supreme Court and the appointment of loyal Governors. At its peak, the Galactic Empire sprawls over much of the known Star Wars galaxy, which consists of millions of habitable star systems and billions more fringe colonies, shipyards, fortress worlds, and outer territories. The Empire's origins are depicted in the prequel film Revenge of the Sith (2005), where it replaces the Galactic Republic at the end of the Clone Wars orchestrated by the Republic's Supreme Chancellor, Palpatine. Palpatine is also secretly the Sith Lord Darth Sidious, who masterminds the war to destroy the Jedi and restore the Sith to power.

Palpatine falsely accuses the Jedi of causing the secessionist Clone Wars to weaken the Republic and gain political power. He manipulates the Galactic Senate into using clone troopers created during the conflict to purge the Jedi. After engineering these threats, Palpatine reorganizes the Republic into a state meant to "ensure the security and continuing stability, and a safe and secure society": the Galactic Empire, with himself as Emperor ad infinitum. The Senate overwhelmingly supports this decision and lauds his apparent resolve, bravery, and selflessness.

With Emperor Palpatine keeping mostly to the shadows, his Sith apprentice, commander-in-chief Darth Vader maintains a more public presence and leads the Imperial forces, acting as a national personification of the Galactic Empire's power. By the time of Episode IV – A New Hope, the faction has transformed into a fully autocratic regime, though it is opposed by the insurgent Alliance to Restore the Republic. The completion of the Death Star, a planet-destroying battle station, allows Emperor Palpatine to instigate a self-coup, dissolving the Imperial Senate and transferring power to Praetor-officers called Imperial Moffs, such as Grand Moff Tarkin.

The Galactic Empire collapses after the events of Return of the Jedi. Its remnants form the First Order in the sequel trilogy, set 30 years later.

Star Wars creator George Lucas sought to make the First Galactic Empire aesthetically and thematically similar to Nazi Germany and to appear to be fascist. Similar to Nazi Germany, the Galactic Empire is a dictatorship based on rigid control of society that dissolved a previous democracy and is led by an all-powerful supreme ruler. The Empire, like the Nazis, desires the creation of totalitarian order and utilizes excessive force and violence to achieve their ends. The title of the Empire's main soldiers, the stormtroopers, is somewhat similar to the name given to Adolf Hitler's Sturmabteilung (SA, "storm department") paramilitary bodyguards.

The visual appearance of Darth Vader in his all-black uniform combined with his fanatical obedience to Palpatine has allusion to the black-uniformed Nazi Schutzstaffel (SS). According to a Lucasfilm-authorized source, Darth Vader's relationship with Palpatine is akin to SS leader Heinrich Himmler's relationship with Hitler. The uniforms of Imperial military officers also bear resemblance to uniforms used in Nazi Germany, as well as 19th century Polish ulans (mounted lancers)—who wore tunics, riding breeches, and boots like the Empire's officers wear—as well as the Imperial officers' cap resembling the field caps historically worn by German and Austrian troops.

In addition to Nazi Germany, there was also at least one portion of the Galactic Empire that was based on the Soviet Union, which is the various military personnel and TIE Fighters that are flying in formation as Palpatine arrives on the second Death Star in Return of the Jedi. According to Lucas, the ceremony for the Emperor's arrival was inspired by October Revolution Day military parades in the Soviet Union.