Castle in the Sky, also known as Laputa: Castle in the Sky, is a 1986 Japanese animated fantasy adventure film written and directed by Hayao Miyazaki. It was produced by Isao Takahata, animated by Studio Ghibli, and distributed by the Toei Company. The film stars the voices of Mayumi Tanaka, Keiko Yokozawa, Kotoe Hatsui [ja], and Minori Terada. In the film, orphans Sheeta and Pazu are pursued by government agent Muska, the army, and a group of pirates. They seek Sheeta's crystal necklace, the key to accessing Laputa, a legendary flying castle hosting advanced technology.

Castle in the Sky was the first film to be animated by Studio Ghibli. Its production team included many of Miyazaki's longtime collaborators, who would continue to work with the studio for the following three decades. The film was partly inspired by Miyazaki's trips to Wales, where he witnessed the aftermath of the 1984–1985 coal miners' strike. The island of Laputa is used to highlight the theme of environmentalism, exploring the relationships between humanity, nature, and technology, a reflection of Miyazaki's ecological philosophy. The young protagonists also provide a unique perspective on the narrative, as a result of Miyazaki's desire to portray "the honesty and goodness of children in [his] work". Many aspects of the film's retrofuturistic style – the flying machines in particular – are influenced by nineteenth-century approaches, which has earned the film a reputation in the modern steampunk genre.

The film was released in Japanese theaters on August 2, 1986. It underperformed expectations at the box office, but later achieved commercial success through rereleases. An English dub commissioned by Tokuma Shoten was distributed in North America by Streamline Pictures, and another dub was produced by Disney in 1998, released internationally by Buena Vista in 2003. The film's score was composed by Joe Hisaishi, who would become a close collaborator of Miyazaki's; Hisaishi also composed a reworked soundtrack for the 2003 English dub. The film was generally acclaimed by critics, though the English dubs received mixed reviews. It was well received by audiences, being voted as one of the greatest animated films in polls conducted by the Agency for Cultural Affairs and Oricon. The film also received several notable accolades, including the Ōfuji Noburō Award at the Mainichi Film Awards and the Anime Grand Prix from Animage. Castle in the Sky has since attained cult status, and has influenced several notable artists working in multiple media.

An airship carrying Sheeta – an orphan girl abducted by the government agent Muska – is attacked by Dola and her air pirate gang, who seek Sheeta's crystal necklace. Attempting to escape, Sheeta falls from the airship but is saved by the crystal's magic, which gently lowers her to the ground. Pazu, an orphan working as a mechanic in a 19th-century mining town, catches her and takes her home to recover. The following morning, he shows Sheeta a photograph his father took of Laputa, a mythical castle on a flying island that Pazu hopes to find. Soon afterward, Dola's gang and Muska's soldiers arrive searching for Sheeta. Fleeing through the town, Pazu and Sheeta fall into a mine shaft, where the crystal again saves them. In the tunnels, they meet Uncle Pom, who reveals deposits of the glowing mineral Aetherium, the same material as Sheeta's crystal.

Sheeta reveals to Pazu her secret name that ties her to Laputa, confirming the legend is real. The army captures the pair and imprisons them in Titus Fort, where Muska shows Sheeta a deactivated robot bearing the same insignia as her crystal and reveals she is heir to the Laputan throne. He releases Pazu in exchange for Sheeta's cooperation in locating Laputa. Returning home, Pazu is captured by Dola's gang, who intend to steal the crystal from Titus Fort. He joins them in an attempt to rescue Sheeta. At the fort, Sheeta recites an ancient phrase taught by her grandmother, inadvertently activating the crystal's power and reanimating the robot. The robot protects her from the soldiers and devastates the fort before being destroyed by the military airship Goliath. Amid the chaos, Pazu and Dola rescue Sheeta, but Muska retains the crystal, whose magic guides him toward Laputa.

Using clues she observed from the crystal, Sheeta helps Pazu persuade Dola to take them to Laputa in exchange for temporarily joining her crew. During the journey, Goliath attacks Dola's airship. Dola detaches the crow's nest – containing Sheeta and Pazu – which functions as a glider tethered to the ship, while Pazu identifies a massive storm where he believes Laputa is hidden. Violent winds destroy the airship and sever the glider's tether, sending Pazu and Sheeta through the storm.

They arrive safely on Laputa, finding it largely deserted except for wildlife and a peaceful robot caretaker. The castle lies in ruins beneath a giant tree growing from the island's center. The army soon arrives and begins looting the castle after capturing Dola's gang. Muska betrays the soldiers, destroys their communications equipment, and takes Sheeta into the castle's core, which houses Laputa's ancient knowledge and weaponry. Using the crystal, he activates the city's defenses and reveals that he, too, descends from the Laputan royal line. After demonstrating Laputa's power by causing a massive explosion over the ocean and destroying Goliath, Muska declares his intention to use the city to dominate the world.

Horrified, Sheeta steals back the crystal and flees, but Muska corners her in Laputa's throne room. Pazu arrives and negotiates a brief truce, allowing Sheeta to teach him the spell of destruction. Together, they recite it, causing Muska to fall to his death as Laputa collapses around them. The giant tree shields Sheeta and Pazu from the destruction and preserves part of the castle, along with Dola's glider, as the island rises into space. Sheeta, Pazu, and Dola's gang escape safely and briefly reunite before parting ways.