The film was ranked as #80 on Bravo's 100 Scariest Movie Moments and the Chicago Film Critics Association named it the 20th scariest film ever made. The film also appeared at #84 on AFI's 100 Years...100 Thrills]], a list of America's most heart-pounding movies. Poltergeist was nominated for three Academy Awards, winning three Saturn Awards and a BAFTA Award.
Steve and Diane Freeling live a quiet life in a California planned community called Cuesta Verde, where Steven is a successful real estate developer and Diane is a housewife who cares for their children Dana, Robbie, and Carol Anne. Carol Anne awakens one night and begins conversing with the family's television set, which is transmitting static following a sign-off. The following night, while the Freelings sleep, Carol Anne fixates on the television set as it transmits static again. Suddenly, an apparition blasts from the television screen and vanishes into the wall, triggering a violent earthquake in the process. As the shaking subsides, Carol Anne announces "They're here."
Bizarre events occur the following day: a drinking glass spontaneously breaks; silverware bends; and furniture moves of its own accord. The phenomena seem benign at first, but quickly begin to intensify. That night, a gnarled backyard tree comes alive and grabs Robbie through the bedroom window. While Diane and Steve rescue Robbie before the demon tree swallows him, Carol Anne is sucked through a portal in her closet. The Freelings realize she has been taken when they hear her voice emanating from a television set.
A group of parapsychologists from UC Irvine — Dr. Lesh, Ryan, and Marty — come to the Freeling house to investigate and determine that the Freelings are experiencing a poltergeist intrusion. They discover that the disturbances involve more than just one ghost. Steve also finds out in an exchange with his boss, Teague, that Cuesta Verde is built where a cemetery was once located.
After Dana and Robbie are sent away for their safety, Dr. Lesh and Ryan call in Tangina Barrons, a spiritual medium. Tangina states that the spirits inhabiting the house are lingering in a different "sphere of consciousness" and are not at rest. Attracted to Carol Anne's life force, these spirits are distracted from the real "light" that has come for them. Tangina then adds that among these ghosts, there is also a demon known as the "Beast", who has Carol Anne under restraint in an effort to manipulate the other spirits.
The assembled group discovers that the entrance to the other dimension is through the children's bedroom closet, while the exit is through the living room ceiling. As the group attempts to rescue Carol Anne, Diane passes through the entrance tied by a rope that has been threaded through both portals. Diane manages to retrieve Carol Anne, and they both drop to the floor from the ceiling, unconscious and covered in prenatal-like fluids. As they recover, Tangina proclaims afterward that the house is now "clean".
Shortly thereafter, the Freelings begin the process of moving elsewhere by packing up their belongings. During their last night in the house, Steve attends a meeting with Teague, while Dana goes on a date, leaving Diane, Robbie, and Carol Anne alone in the house. The "Beast" then ambushes Diane and the children, attempting a second kidnapping. Though at first trapped in the house, Diane and the children eventually escape to the outside only to discover coffins and rotting corpses erupting out from the ground in their yard and throughout the neighborhood. As Steve and Dana return home to the mayhem, Steve realizes that rather than relocating the cemetery for the development of Cuesta Verde, Teague merely had the headstones moved and the bodies left behind, desecrating the burial grounds. The Freelings flee Cuesta Verde while the house itself implodes into another dimension, to the astonishment of onlookers. The family checks into a hotel for the night, and Steve shoves the room's television outside onto the balcony.
- Craig T. Nelson as Steve Freeling, a real estate agent. He is immediately disturbed when the events begin. When Carol Anne is abducted, he has a team of parapsychologists come to the house to investigate.
- JoBeth Williams as Diane Freeling, Steve's wife. She is excited by the ghosts at first, but becomes disturbed upon Carol Anne's abduction, and eventually rescues her.
- Heather O'Rourke as Carol Anne Freeling, the 5-year-old daughter of Steve and Diane. She is the first to know of the ghosts' presence.
- Oliver Robins as Robbie Freeling, the 8-year-old son of Steve and Diane. He is immediately fearful of the tree and clown that later attack him. However, when the clown attacks him, Robbie is able to destroy the clown fearlessly.
- Dominique Dunne as Dana Freeling, the 16-year-old daughter of Steve and Diane. She is the last to know and upon Carol Anne's abduction, so afraid that she stays at a friend's house for the majority of the film's second half.
- Beatrice Straight as Dr. Lesh, a parapsychologist who determines the disturbances to be a poltergeist intrusion rather than a typical haunting.
- Martin Casella as Marty, an assistant to Dr. Lesh, who is so disturbed, he decides not to return.
- Richard Lawson as Ryan, an assistant to Dr. Lesh, who is fascinated by the events, and stays until Carol Anne is rescued.
- Zelda Rubinstein as Tangina Barrons, a clairvoyant. Steve is skeptical of her at first, but she soon proves herself.
- James Karen as Mr. Teague, Steve's boss, who turns out to be responsible for the disturbances through committing the act of sacrilege.