Signs is a 2002 American science fiction horror thriller film written and directed by M. Night Shyamalan and produced by Shyamalan, Frank Marshall, Kathleen Kennedy and Sam Mercer. The film was produced by Touchstone Pictures, Blinding Edge Pictures and The Kennedy/Marshall Company. It was distributed by Buena Vista Pictures. Starring Mel Gibson and Joaquin Phoenix, the story focuses on a former Episcopal priest named Graham Hess who discovers a series of crop circles in his cornfield and that the phenomenon is a result of extraterrestrial life. Signs explores the themes of faith, kinship, and extraterrestrials.

Signs premiered in theaters on August 2, 2002. The film was a financial success, grossing $408 million on a $72 million budget, becoming the seventh-highest-grossing film of 2002, and was met with positive reviews from critics, with many praising its atmosphere, performances, cinematography, score and story, but others criticizing aspects of the script. The film was nominated for multiple awards, including those from the Online Film Critics Society and the Empire Awards. The film also won an award from the American Society of Composers, Authors and Publishers. The high definition Blu-ray Disc edition of the film featuring the director's audio commentary, the making of the film and deleted scenes was released in the United States on June 3, 2008. The original motion picture soundtrack, which was composed by James Newton Howard, was released on the opening day by the Hollywood Records label.

Former Episcopal priest Graham Hess lives on a rural farm in Doylestown, Pennsylvania, with his asthmatic preteen son, Morgan, and young daughter, Bo, who has a fixation on contaminated water. Graham's younger brother Merrill, a failed minor league baseball player, has been helping the family since Graham's wife Colleen died in a traffic collision six months earlier. Graham abandoned the church in the aftermath of the incident.

A large crop circle appears in the Hesses' cornfield, which they initially attribute to vandals; however, other similar crop circles begin appearing globally. When lights from unseen objects begin appearing over more and more of Earth's cities, speculation of an alien invasion grows worldwide, including at the Hesses' farm. Morgan believes he hears alien noises on Bo's old baby monitor, while Merrill becomes convinced after seeing footage from Brazil of an unidentified humanoid creature. On successive nights, Graham sees an intruder standing on the roof of his home and in the cornfield, yet remains adamant there is a reasonable explanation for all events.

Graham receives a phone call from veterinarian Ray Reddy, the man responsible for his wife's death, and drives to his house. Expressing remorse for Colleen's death, Reddy tells Graham of a creature he has locked in his pantry and, believing they avoid water, he leaves for the lake. Graham enters the house and attempts to see under the pantry door, when a clawed hand swipes at him and he severs the creature's fingers in a panic. Having seen this, Graham decides to protect his house by boarding up the windows and doors. That night, an intruder breaks in, and the family takes refuge in the basement, where Morgan has an asthma attack, but despite leaving his medication upstairs, Morgan survives the night.

The next morning, when they hear radio reports that all the phenomena in the world's skies have stopped, the family emerges from the basement. They find the creature from Reddy's house in their living room; Graham recalls Colleen's dying words, "swing away", prompting Merrill to swing at the creature with his baseball bat, knocking the creature into glasses of water left out by Bo, which weakens it. The creature sprays Morgan with a mysterious gas, rendering him unconscious; Graham rescues his son and administers Morgan's medication, realizing that his son's constricted lungs prevented him from inhaling the toxins, an act that Graham attributes to the intervention of a higher power. By winter, the Hess family has recovered from the ordeal, and Graham returns to the church.

M. Night Shyamalan was a fan of the film You Can Count on Me and cast Rory Culkin and Mark Ruffalo. However, Ruffalo required surgery for a tumor behind his ear and was unable to work on the film, so a week before filming the role was recast with Joaquin Phoenix. The role of Graham was originally written to be an older man. Shyamalan approached Paul Newman for the role, but he declined due to lack of interest, and he also approached Clint Eastwood, who declined due to scheduling conflicts.

Shyamalan has said that the film's concept is the combination of two ideas – a family finding a crop circle on their property, and an "end of the world" premise.