Ghostbusters is a 1984 American supernatural comedy film directed and produced by Ivan Reitman, and written 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, Ernie Hudson, and William Atherton 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 venture 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 on November 19, 2021.