Ghostbusters II is a 1989 American supernatural comedy film directed by Ivan Reitman and written by Dan Aykroyd and Harold Ramis. The film stars Bill Murray, Aykroyd, Sigourney Weaver, Ramis, Rick Moranis, Ernie Hudson, and Annie Potts. It is the sequel to the 1984 film Ghostbusters and the second film in the Ghostbusters franchise. Set five years after the events of the first film, the Ghostbusters have been sued and put out of business after the destruction caused during their battle with the deity Gozer the Gozerian. When a new paranormal threat emerges, the Ghostbusters reunite to combat it and save the world.

After the success of Ghostbusters, Columbia Pictures wanted a sequel but struggled to overcome objections from the cast and crew. As with the first film, Aykroyd and Ramis collaborated on the script, which went through many variations. The pair wanted to convey a message about the consequences of negative human emotions in large cities. They settled on the idea of negative feelings creating a mass of supernatural slime beneath New York City that empowers malevolent spirits. With a budget of $30–40 million, filming took place between November 1988 and March 1989 in New York City and Los Angeles. Production was rushed and large sections of the film were scrapped after poorly received test screenings. New scenes were written and filmed during re-shoots between March and April 1989, only two months before its release.

Ghostbusters II was released on June 16, 1989, to generally negative reviews. Critics responded unfavorably to what they perceived as largely a copy of the original and a softening of its cynical, dark humor to be more family-friendly, although the performances of Peter MacNicol and Rick Moranis were repeatedly singled out for praise. As the sequel to the then-highest-grossing comedy film of all time, Ghostbusters II was expected to dominate the box office. Instead, the film earned $215.4 million during its theatrical run compared with the original's $282.2 million, making it the eighth-highest-grossing film of the year. Columbia Pictures deemed it a failure, effectively dissuading Murray from participating in a third Ghostbusters film. Its soundtrack single, "On Our Own" by Bobby Brown, was a success, spending 20 weeks on the United States music charts.

The film failed to replicate the cultural impact and following of Ghostbusters and was seen as responsible for stalling the franchise for decades, though its reception has improved over time. The film spawned a series of merchandise including video games, board games, comic books, music, toys, and haunted houses. Despite the relative failure of Ghostbusters II, a second sequel was pursued through to the early 2010s. Following the mixed reviews and financial underperformance of the 2016 series reboot, the series returned to the original film canon with Ghostbusters: Afterlife (2021) and Ghostbusters: Frozen Empire (2024).

Five years after saving New York City from destruction by the shapeshifting god Gozer, the Ghostbusters have been sued for the property damage incurred and barred from investigating the supernatural, forcing them out of business. Ray Stantz now owns an occult bookstore and works a side job alongside Winston Zeddemore as unpopular children's entertainers; Egon Spengler works in a laboratory experimenting with human emotions; and Peter Venkman hosts a television talk show about psychics.

Dana Barrett, Peter's ex-girlfriend, has an infant son named Oscar with her ex-husband and works at an art museum restoring artwork. She contacts the Ghostbusters after Oscar's baby stroller rolls, seemingly independently, into a busy intersection. At the museum, a painting of Vigo the Carpathian, a 16th-century European tyrant and powerful magician, comes to life and enslaves Dana's boss, Janosz Poha. Vigo orders Janosz to bring him a child to possess, allowing him to escape the confines of his painting and live again to conquer the world. Because of his infatuation with Dana, Janosz chooses Oscar.

Meanwhile, the Ghostbusters excavate the intersection where Oscar's stroller stopped and discover a river of slime running through the abandoned Beach Pneumatic Transit system. Ray obtains a sample but is attacked by the slime and accidentally breaks a pipe that falls onto a power line, causing a citywide blackout. The Ghostbusters are arrested and taken to court for the damage and for investigating the supernatural. Upon presentation as evidence, the slime sample responds physically to the judge's tirade against the Ghostbusters and then explodes, manifesting the ghosts of the Scoleri brothers, whom he had sentenced to death. The Ghostbusters capture the ghosts in exchange for a dismissal of the charges and the right to resume their business.

One night, the slime invades Dana's apartment, attacking her and Oscar. She seeks refuge with Peter, and they rekindle their relationship. The Ghostbusters discover the slime reacts to emotions and suspect it has amassed from the negative emotions of New Yorkers. Determining Vigo and the slime are connected, Egon, Ray, and Winston investigate the river of slime, but they are pulled in. They emerge at the museum and begin fighting each other until Egon realizes the slime's negative energy is influencing them. The Ghostbusters tell the mayor of their discoveries but are dismissed; his assistant Jack Hardemeyer has them committed to a psychiatric hospital to protect the mayor's political interests. A spirit appearing as Janosz kidnaps Oscar, and Dana pursues them into the museum, which is then covered with impenetrable slime.