Plot
Dr. Malcolm Crowe (Bruce Willis), a child psychologist in Philadelphia, returns home one night with his wife, Anna Crowe (Olivia Williams), after having been honored for his work. Anna tells Malcolm that everything is second to his work. The two then discover that they are not alone; a young man appears brandishing a gun. He says that he does not want to be afraid anymore and accuses Crowe of failing him. Malcolm recognizes him as Vincent Gray (Donnie Wahlberg), a former patient whom he treated as a child for hallucinations. Vincent shoots Malcolm in the abdomen, before turning the gun on himself.

The next autumn, Malcolm begins working with another patient, nine-year-old Cole Sear (Haley Joel Osment), who has a condition similar to Vincent's. Malcolm becomes dedicated to the boy, though he is haunted by doubts over his ability to help him after his failure with Vincent. Meanwhile, his relationship with his wife has deteriorated to the point where she ignores him and refuses to talk to him. Malcolm believes that Anna may be contemplating a romance with a coworker who keeps coming around the house, although this elicits sadness, rather than anger, from him. Malcolm also repeatedly has difficulty opening the door to his basement office.

Once Malcolm earns his trust, Cole eventually confides in him that he "sees dead people... walking around like regular people". One that tries to hurt Cole is only heard as a voice who pleads with Cole to let him out of a dark cupboard, then yells that he didn't steal "the Master's horse" and threatens to attack Cole. Another ghost who appears to Cole is an overworked wife, abused by her husband, who has slit her wrists. A third ghost is a boy with a large gunshot exit wound on the back of his head who asks Cole to come with him to find his father's gun.

At first, Malcolm thinks Cole is delusional and plans to drop him. Remembering Vincent, the psychologist listens to a session between them in 1987. On the tape, Malcolm left the room and when he returned Vincent was crying. Turning up the volume all the way, Malcolm hears a weeping Spanish man and now believes that Cole is telling the truth and that Vincent may have had the same ability to perceive ghosts. He suggests to Cole that he should try to find a purpose for his gift by communicating with the ghosts and perhaps aid them with their unfinished business on Earth. Cole at first does not want to since the ghosts terrify him, but he finally decides to try it. He talks to one of the ghosts, a very ill girl who appears in his bedroom and promptly vomits in his tent. He finds where the girl, Kyra Collins (Mischa Barton), lived and goes to her house during her funeral reception with Malcolm. Kyra died after a prolonged illness and funeral guests note that Kyra's younger sister is starting to get sick, too. Kyra's ghost appears and gives Cole a box, which is opened to reveal a videotape. When Cole gives it to Kyra's father, the videotape shows Kyra's mother putting floor cleaner fluid in Kyra's food while she cared for Kyra during her illness.

Learning to live with the ghosts, Cole starts to fit in at school and gets the lead in the school play, which Malcolm attends. The doctor and patient depart on positive terms and Cole suggests to Malcolm that he should try speaking to Anna while she is asleep. On the way home, Cole confesses his secret to his mother, Lynn (Toni Collette). Although his mother at first does not believe him, Cole soon tells Lynn that her own mother once went to see her perform in a dance recital one night when she was a child, and that Lynn was not aware of this because her mother stayed in the back of the audience where she could not be seen. He also tells her that the answer to a question she asked when alone at her mother's grave, "Do I make you proud?", was "Every day". Lynn tearfully accepts this as the truth.

Malcolm returns to his home, where he finds his wife asleep on the couch with the couple's wedding video playing, not for the first time. As she sleeps, Anna asks her husband why he left her. Then her hand drops Malcolm's wedding ring, which he suddenly discovers he has not been wearing. Malcolm remembers what Cole said about ghosts and the psychologist realizes that he was actually killed by Vincent and was unknowingly dead the entire time he was working with Cole. Due to Cole's efforts, Malcolm's unfinished business—rectifying his failure to understand and help Vincent—is finally complete. Recalling Cole's advice, Malcolm speaks to his sleeping wife and fulfills the second reason he returned, saying she was "never second", and that he loves her. Letting her live her own life, he is free to leave the world of the living.

Reception
The film received positive reviews from critics, with an 85% 'fresh' rating on Rotten Tomatoes, and 64 rating on Metacritic.

The film had a production budget of approximately $40 million (plus $25 million for prints and advertising). It grossed $26.6 million in its opening weekend and spent five weeks as the No. 1 film at the U.S. box office. It earned $293,506,292 in the United States and a worldwide gross of $672,806,292, ranking it 35th on the list of box-office money earners in the U.S. as of April 2010. In the United Kingdom, it was given at first a limited release at 9 screens, and entered at No. 8 before climbing up to No. 1 the next week with 430 theatres playing the film.

By vote of the members of the Science Fiction and Fantasy Writers of America, The Sixth Sense was awarded the Nebula Award for Best Script during 1999. The film was No. 71 on Bravo's 100 Scariest Movie Moments, for the scene where Cole encounters a female ghost in his tent. It was also recently named the 89th Best Film of all time by the American Film Institute during 2007.

The line "I see dead people" from the film became a popular catchphrase after its release, scoring No. 44 on AFI's 100 Years...100 Movie Quotes. The Sixth Sense also scored 60th place on AFI's 100 Years...100 Thrills, honoring America's most "heart pounding movies". It also appears on AFI's 100 Years...100 Movies (10th Anniversary Edition), a list of America's 100 greatest movies of all time.

Accolades
The Sixth Sense has received numerous awards and nominations, with nomination categories ranging from those honoring the film itself (Best Film), to its writing, editing, and direction (Best Direction, Best Editing, Best Original Screenplay), to its cast's performance (Best Actor / Actress). Especially lauded was the supporting role of actor Haley Joel Osment, whose nominations include an Academy Award, a Broadcast Film Critics Association Award, and a Golden Globe Award. Overall, The Sixth Sense was nominated for six Academy Awards and four British Academy Film Awards, but won none. The film received three nominations from the People's Choice Awards and won all of them, with lead actor Bruce Willis being honored for his role. The Satellite Awards nominated the film in four categories, with awards being received for writing (M. Night Shyamalan) and editing (Andrew Mondshein). Supporting actress Toni Collette was nominated for both an Academy Award and a Satellite award for her role in the film. James Newton Howard was honored by the American Society of Composers, Authors and Publishers for his composition of the music for the film.

In 2013, the Writers Guild of America ranked the screenplay #50 on its list of 101 Greatest Screenplays ever written.

American Film Institute lists
AFI's 100 Years...100 Thrills – No. 60
AFI's 100 Years...100 Movie Quotes:
"I see dead people." – No. 44
AFI's 100 Years...100 Movies (10th Anniversary Edition) – No. 89

Production
According to the book DisneyWar, Disney's David Vogel read Shyamalan's speculative script and instantly loved it. Without obtaining approval from his boss, Vogel bought the rights to the script, despite the high price of US$2 million and the stipulation that Shyamalan could direct the film. Disney later dismissed Vogel as President of Walt Disney Pictures, and Vogel left the company. Disney, apparently in a show of little confidence in the film, sold the production rights to Spyglass Entertainment, and kept only a 12.5% distribution fee for itself.

The color red is intentionally absent from most of the film, but is used prominently in a few isolated shots for "anything in the real world that has been tainted by the other world" and "to connote really explosively emotional moments and situations". Examples include the door of the church where Cole seeks sanctuary; the balloon, carpet, and Cole's sweater at the birthday party; the tent in which he first encounters Kyra; the volume numbers on Crowe's tape recorder; the doorknob on the locked basement door where Malcolm's office is located; the shirt that Anna wears at the restaurant; Kyra's mother's dress at the wake; and the shawl wrapped around the sleeping Anna.

All of the clothes Malcolm wears during the film are items he wore or touched the evening before his death, which included his overcoat, his blue rowing sweatshirt and the different layers of his suit. Though the filmmakers were careful about clues of Malcolm's true state, the camera zooms slowly towards his face when Cole says "I see dead people". In a special feature the filmmakers mention they initially feared this would be too much of a giveaway, but decided to leave it in.