The Incredible Shrinking Man is a 1957 American science fiction film directed by Jack Arnold, based on Richard Matheson's 1956 novel, The Shrinking Man. The film stars Grant Williams as Scott and Randy Stuart as Scott's wife, Louise. While relaxing on a boat, Scott is enveloped by a strange fog. Months later, he discovers that he appears to be shrinking. By the time Scott has reached the height of a small boy, his condition becomes known to the public. When he learns there is no cure for his condition, he lashes out at his wife. As Scott shrinks to the point where he can fit into a dollhouse, he has a battle with his family cat, leaving him lost and alone in his basement, where he is now smaller than the average insect.

The film's storyline was expanded by Matheson after he had sold the story to Universal-International Pictures Co., Inc. He also completed the novel upon which the film is based while production was underway. Matheson's script was initially written in flashbacks, and Richard Alan Simmons rewrote it using a more conventional narrative structure. Director Jack Arnold initially wanted Dan O'Herlihy to play Scott, but O'Herlihy turned down the role, leading Universal to sign Williams as the lead. Filming began on May 31, 1956. Scenes involving special effects were shot throughout production, while others used the large sets of Universal's backlot. Production went over budget, and filming had to be extended; certain special effects shots required reshooting. Williams was constantly being injured on set.

Before the film's release in New York City on February 22, 1957, its ending first went to test audiences who felt the character's fate should be changed. The director's original ending remained in the film. The film grossed $1.43 million in the United States and Canada and was among the highest-grossing science fiction films of the 1950s. A sequel, The Fantastic Little Girl, originally penned by Matheson, never went into production. A remake was developed years later, eventually becoming the comedy The Incredible Shrinking Woman (1981). Other remakes were planned in the early 2000s, one of which was to star Eddie Murphy in a more comedic variation on the film. A new adaptation was announced in 2013, with Matheson writing the screenplay with his son Richard Christian Matheson. In 2009, the film was selected for preservation in the United States National Film Registry by the Library of Congress as being "culturally, historically, or aesthetically significant."

Robert Scott Carey, known as "Scott," is on vacation with his wife, Louise, when a strange mist envelops him. Six months later, he observes that his clothes are too large, suspects he is shrinking, and seeks medical advice. Initially, his doctor denies that Carey is shrinking. Later, the doctor confirms the shrinking through X-rays and refers him to a medical research institute. The institute determines that Carey's exposure to the mist, combined with earlier exposure to a pesticide, rearranged his molecular structure, causing him to shrink. Carey informs Louise that, given his predicament, she is free to leave him. Louise promises to stay, and as she does, Carey's wedding ring slips off his finger.

Carey's condition turns him into a national curiosity. Media attention forces him into seclusion within his home. Advised to sell his story, Carey starts a journal detailing his experiences. An antidote is discovered, halting his shrinking, but doctors caution that he will remain three feet tall for the rest of his life unless a solution is found to reverse his condition. Emotionally shattered, Carey meets Clarice, a carnival worker and dwarf, who is exactly his height. Clarice encourages Carey, inspiring him to continue his journal. Later, he notices he is now shorter than Clarice and dejectedly runs home.

Carey shrinks small enough to live in a dollhouse and becomes more tyrannical. When Louise leaves home on an errand, he falls into his basement after Butch, the family cat, attacks him. Louise returns and assumes Butch ate Carey after finding a bloody scrap of Carey's clothing. Louise prepares to move out, with Carey's brother, Charlie, assisting.

Carey faces significant challenges navigating his basement and is unable to climb the stairs back up, deciding to wait for Louise to come down. The water heater bursts, but when Charlie and Louise come to investigate, Carey is too small for them to hear his screams for help. He battles a large spider while searching for food and shelter. He ultimately kills the spider with a straight pin and collapses in exhaustion. He awakens, small enough to escape the basement through one of the netting squares of a window screen. Carey accepts his fate of shrinking to microscopic size. He is no longer afraid, concluding that no matter how small he becomes, he will still matter in the universe because God will know he exists.

Cast adapted from the American Film Institute.