Ghostbusters is a 1984 American supernatural comedy film directed and produced by Ivan Reitman, with a screenplay by Dan Aykroyd and Harold Ramis. It stars Bill Murray, Aykroyd and Ramis as Peter Venkman, Ray Stantz and Egon Spengler, three eccentric parapsychologists who start a ghost-catching business in New York City. It also stars Sigourney Weaver and Rick Moranis, and features Annie Potts, William Atherton, and Ernie Hudson in supporting roles.
Based on his own fascination with spirituality, Aykroyd conceived Ghostbusters as a project starring himself and John Belushi, in which they would adventure through time and space battling supernatural threats. Following Belushi's death in 1982, and with Aykroyd's concept deemed financially impractical, Ramis was hired to help rewrite the script to set it in New York City and make it more realistic. It was the first comedy film to employ expensive special effects, and Columbia Pictures, concerned about its relatively high $25–30 million budget, had little faith in its box office potential. Filming took place from October 1983 to January 1984, in New York City and Los Angeles. Due to competition for special effects studios among various films in development at the time, Richard Edlund used part of the budget to found Boss Film Studios, which employed a combination of practical effects, miniatures, and puppets to deliver the ghoulish visuals.
Ghostbusters was released on June 8, 1984, to critical acclaim and became a cultural phenomenon. It was well received for its blend of comedy, action, and horror, and Murray's performance was often singled out for praise. It earned $282.2 million during its initial theatrical run, making it the second-highest-grossing film of 1984 in the United States and Canada, and the then-highest-grossing comedy ever. It was the number-one film in theaters for seven consecutive weeks and one of only four films to gross more than $100 million that year. Further theatrical releases have increased the total gross to around $295.2 million, making it one of the most successful comedy films of the 1980s. In 2015, the Library of Congress selected it for preservation in the National Film Registry. Its theme song, "Ghostbusters" by Ray Parker Jr., was also a number-one hit.
With its effect on popular culture, and a dedicated fan following, the success of Ghostbusters launched a multi-billion dollar multimedia franchise. This included the popular animated television series The Real Ghostbusters (1986), its sequel Extreme Ghostbusters (1997), video games, board games, comic books, clothing, music, and haunted attractions. Ghostbusters was followed in 1989 by Ghostbusters II, which fared less well financially and critically, and attempts to develop a second sequel paused in 2014 following Ramis's death. After a 2016 reboot received mixed reviews and underperformed financially, a second sequel to the 1984 film, Ghostbusters: Afterlife, was released in November 2021.
After Columbia University parapsychology professors Peter Venkman, Ray Stantz, and Egon Spengler experience their first encounter with a ghost at the New York Public Library, the university dean dismisses the credibility of their paranormal-focused research and fires them. The trio responds by establishing "Ghostbusters", a paranormal investigation and elimination service operating out of a disused firehouse. They develop high-tech nuclear-powered equipment to capture and contain ghosts, although business is initially slow.
After a paranormal encounter in her apartment, cellist Dana Barrett calls the Ghostbusters. She recounts witnessing a demonic dog-like creature utter a single word: "Zuul". Ray and Egon research Zuul and details of Dana's building while Peter inspects her apartment and unsuccessfully attempts to seduce her. The Ghostbusters are hired to remove a gluttonous ghost, Slimer, from the Sedgewick Hotel. Having failed to properly test their equipment, Egon warns the group that crossing the energy streams of their proton pack weapons could cause a catastrophic explosion. They capture the ghost and deposit it in an ecto-containment unit under the firehouse. Supernatural activity rapidly increases across the city and the Ghostbusters become famous; they hire a fourth member, Winston Zeddemore, to cope with the growing demand.
Suspicious of the Ghostbusters, Environmental Protection Agency inspector Walter Peck asks to evaluate their equipment but Peter rebuffs him. Egon warns that the containment unit is nearing capacity and supernatural energy is surging across the city. Peter meets with Dana and informs her Zuul was a demigod worshipped as a servant to "Gozer the Gozerian", a shapeshifting god of destruction. Upon returning home, she is possessed by Zuul; a similar entity possesses her neighbor, Louis Tully. Peter arrives and finds the possessed Dana/Zuul claiming to be "the Gatekeeper". Louis is brought to Egon by police officers and claims he is "Vinz Clortho, the Keymaster". The Ghostbusters agree to keep the pair separated.
Peck returns with law enforcement and city workers to have the Ghostbusters arrested and their containment unit deactivated, causing an explosion that releases the captured ghosts. Louis/Vinz escapes in the confusion and makes his way to the apartment building to join Dana/Zuul. In jail, Ray and Egon reveal Ivo Shandor, leader of a Gozer-worshipping cult, designed Dana's building to function as an antenna to attract and concentrate spiritual energy to summon Gozer and bring about the apocalypse. Faced with supernatural chaos across the city, the Ghostbusters convince the mayor to release them.
The Ghostbusters travel to the apartment building roof as Dana/Zuul and Louis/Vinz open the gate between dimensions and transform into demonic dogs. Gozer appears as a woman and attacks the Ghostbusters then disappears when they attempt to retaliate. Her disembodied voice demands the Ghostbusters "choose the form of the destructor". Ray inadvertently recalls a beloved corporate mascot from his childhood, and Gozer reappears as a gigantic Stay Puft Marshmallow Man that begins destroying the city. Against his earlier advice, Egon instructs the team to cross their proton energy streams at the dimensional gate. The resulting explosion destroys Gozer's avatar, banishing it back to its dimension, and closes the gateway. The Ghostbusters rescue Dana and Louis from the wreckage and are welcomed on the street as heroes.