L'univers de Star Wars se déroule dans une galaxie théâtre d'affrontements entre les Chevaliers Jedi et les Seigneurs noirs des Sith, personnes sensibles à la Force, un champ énergétique mystérieux leur procurant des pouvoirs psychiques. Les Jedi maîtrisent le côté lumineux de la Force, pouvoir bénéfique et défensif, pour maintenir la paix dans la galaxie. Les Sith utilisent le côté obscur, pouvoir nuisible et destructeur, pour leur usage personnel et pour dominer la galaxie. Les Sith vont par deux : un maître et un apprenti.
L'univers de Star Wars est amorcé avec le conflit entre la République galactique et la Confédération des systèmes indépendants, alliance de planètes séparatistes. Cette confédération entraîne des dirigeants de la République dans des affaires ingérables à cause des manigances du Chancelier Suprême Palpatine, chef d'État de la République, qui dit servir la démocratie tout en visant secrètement à établir un empire. Pour rétablir la paix, les Jedi combattent les ennemis de la République, sans savoir que les deux camps sont manipulés par les Seigneurs Sith (Palpatine étant en réalité le Seigneur Sith Dark Sidious). Les Jedi, comme les Sith, sont sensibles à la Force, une capacité d'origine physiologique qui permet à leurs détenteurs d'acquérir certains pouvoirs surnaturels.
L'univers de Star Wars tourne autour des tentatives de séparation d'un groupe favorable à un empire de la République galactique. Pour ce faire, les séparatistes entraînent des dirigeants de la République dans des affaires ingérables grâce aux manigances du Chancelier Suprême Palpatine, qui dit servir la démocratie tout en étant favorable à un empire. Pour maintenir la paix en place, les Jedi combattent les ennemis de la République, mais ceux-ci doivent faire face aux Seigneurs Sith (dont Palpatine est membre, sous le nom de Dark Sidious), tous sont sensibles à la Force, une capacité d'origine physiologique qui permet à leurs détenteurs d'acquérir certains pouvoirs surnaturels.
In response to taxation on trade routes in the Galactic Republic, the Trade Federation organizes a blockade of battleships around the planet Naboo. Supreme Chancellor Valorum dispatches Jedi Master Qui-Gon Jinn and his apprentice Obi-Wan Kenobi to negotiate with the Trade Federation leadership to end the blockade. Darth Sidious, a Sith Lord and the Trade Federation's secret adviser, orders Federation Viceroy Nute Gunray to kill the Jedi and invade Naboo with an army of battle droids. The Jedi flee to Naboo, where Qui-Gon saves Gungan outcast Jar Jar Binks from being killed during the invasion. Indebted to the Jedi, Jar Jar leads them to an underwater Gungan city. There the Jedi try but fail to persuade the Gungan leader, Boss Nass into helping the people of Naboo, though they are able to obtain transportation to Theed, the capital city on the surface. They rescue Queen Amidala, the ruler of the Naboo people, and escape the planet on her royal starship, which is damaged as they pass the Federation blockade.
During a space battle over Coruscant between the Galactic Republic and the Separatist Alliance, Jedi Knights Obi-Wan Kenobi and Anakin Skywalker lead a mission to rescue the kidnapped Supreme Chancellor Palpatine from Separatist commander General Grievous. After infiltrating Grievous' flagship, the Jedi engage Count Dooku in a lightsaber duel, which ends with Anakin killing Dooku at Palpatine's urging. Grievous flees the battle-torn cruiser, which the Jedi crash-land on Coruscant. There, Anakin reunites with his wife, Padmé Amidala, who reveals she is pregnant. Initially excited, Anakin begins to have premonitions of Padmé dying in childbirth.
On July 2, a 500 km wide alien mothership enters Earth's orbit and deploys several dozen saucer-shaped "destroyer" spacecraft, each 15 miles (24 km) wide. As they take position over some of Earth's major cities, David Levinson (Jeff Goldblum), an MIT graduate working for a cable company in New York City, discovers hidden transmissions in Earth's satellites which he realizes is a timer counting down to a coordinated attack by the aliens. With the support of his estranged wife Constance Spano (Margaret Colin), the White House Communications Director, he and his father Julius (Judd Hirsch) gain entrance into the Oval Office to notify President Thomas J. Whitmore (Bill Pullman) about the attack. Whitmore orders large-scale evacuations of the targeted cities, but the aliens attack with advanced directed-energy weapons before these can be carried out. Whitmore, portions of his staff, and the Levinsons narrowly escape aboard Air Force One as Washington, D.C. is destroyed.
The galaxy is in a civil war, and spies for the Rebel Alliance have stolen plans to the Galactic Empire's Death Star, a heavily armed and armored space station capable of destroying entire planets. Rebel leader Princess Leia is in possession of the plans, but her ship is captured by Imperial forces under the command of the evil Lord Darth Vader. Before she is captured Leia hides the plans in the memory of an astromech droid called R2-D2, along with a holographic recording. The droid, accompanied by fellow protocol droid C-3PO, escape from the captured ship to the desert planet Tatooine.
In 1988, following his mother's death, a young Peter Quill is abducted from Earth by the Ravagers, a group of space pirates led by Yondu Udonta. Twenty-six years later on the planet Morag, Quill steals an orb, after which Korath, a subordinate to the fanatical Kree, Ronan, intercepts him. Although Quill escapes with the orb, Yondu discovers his theft and issues a bounty for his capture, while Ronan sends the assassin Gamora after the orb.
Dr. Ryan Stone (Sandra Bullock) is a biomedical engineer aboard the NASA space shuttle Explorer for her first space mission, STS-157. Veteran astronaut Matt Kowalski (George Clooney) is commanding his final mission. During a spacewalk to service the Hubble Space Telescope and Stone's upgrades to the Telescope, Mission Control in Houston warns the team about a Russian missile strike on a defunct satellite, which has inadvertently caused a chain reaction forming a cloud of debris in space. Mission Control orders that the mission be aborted and the crew begin re-entry immediately because the debris is speeding towards the shuttle. Communication with Mission Control is lost shortly thereafter.
Crop blight has made growing food on Earth nearly impossible, threatening the existence of humanity. Joe Cooper, a widowed former NASA pilot, runs a farm with his father-in-law Donald, son Tom, and daughter Murphy. Murphy believes her bedroom is haunted by a poltergeist. When the "ghost" creates a pattern of dust on the floor, Cooper realizes an unknown intelligence is using gravity to communicate, and interprets the pattern as geographic coordinates, which Cooper and Murphy follow to a secret NASA installation.
Ten years after the Trade Federation's invasion of Naboo, the Galactic Republic is threatened by a Separatist movement organized by former Jedi Master Count Dooku. Senator Padmé Amidala comes to Coruscant to vote on a plan to create an army of the Republic to assist the Jedi against this threat. Narrowly avoiding an assassination attempt upon arrival, she is placed under the protection of Jedi Knight Obi-Wan Kenobi and his apprentice Anakin Skywalker. The two Jedi thwart another attempt on her life and subdue the assassin, Zam Wesell, a shape-shifter who is killed by her bounty hunter client with a toxic dart before she can reveal his identity. The Jedi Council assigns Obi-Wan to identify and capture the bounty hunter, while Anakin is assigned to escort Padmé back to Naboo, where the two fall in love.
In the 2030s, the crew of Ares III, a manned mission to Mars, has established a temporary artificial habitat, called the Hab, on Mars, where they are to stay for two months and depart back to Earth in their orbital probe. Eighteen days into the Mars mission, however, a massive Martian storm hits the base and the crew is forced to abandon the planet and launch themselves because of the danger that their escape vehicle will collapse and leave them stranded. While evacuating, astronaut Mark Watney is lost and presumed dead as his biomonitor is damaged. With the lives of her crew at stake, mission commander Melissa Lewis is forced to leave the planet, leaving Watney behind.
Luke Skywalker initiates a plan to rescue Han Solo from the crime lord Jabba the Hutt with the help of Princess Leia, Lando Calrissian, Chewbacca, C-3PO, and R2-D2. Leia infiltrates Jabba's palace on Tatooine disguised as a bounty hunter with Chewbacca as her prisoner. Lando is already there disguised as a guard. Leia releases Han from his carbonite prison, but she is captured and enslaved. Luke arrives soon afterward but after a tense standoff, he is captured. After Luke survives his battle with Jabba's Rancor, Jabba sentences him and Han to death by feeding them to the Sarlacc. Luke frees himself and battles Jabba's guards. During the chaos, Boba Fett, who has remained at Jabba's palace since delivering Han, attempts to attack Luke, but Han inadvertently knocks him into the Sarlacc pit. Meanwhile, Leia strangles Jabba to death, and Luke destroys Jabba's sail barge as the group escapes. While the others rendezvous with the Rebel Alliance, Luke returns to Dagobah where he finds that Yoda is dying. Before he dies, Yoda confirms that Darth Vader, once known as Anakin Skywalker, is Luke's father, and there is "another Skywalker". The spirit of Obi-Wan Kenobi confirms that this other Skywalker is Luke's twin sister, Leia. Obi-Wan tells Luke that he must fight Vader again to defeat the Empire.