Dirty Harry is a 1971 American action-thriller film produced and directed by Don Siegel, the first in the Dirty Harry series. Clint Eastwood plays the title role, in his first appearance as San Francisco Police Department (SFPD) Inspector "Dirty" Harry Callahan. The film drew upon the real-life case of the Zodiac Killer as the Callahan character seeks out a similar vicious psychopath.

Dirty Harry was a critical and commercial success and set the style for a whole genre of police films. It was followed by four sequels: Magnum Force in 1973, The Enforcer in 1976, Sudden Impact in 1983, and The Dead Pool in 1988.

In 2012, the film was selected for preservation in the United States National Film Registry by the Library of Congress as being "culturally, historically, and aesthetically significant".

A psychopathic sniper, later referred to as "Scorpio", shoots a woman while she swims in a San Francisco skyscraper rooftop pool. He leaves behind a threatening letter demanding he be paid $100,000 or he will kill more people. The note is found by SFPD Inspector Harry Callahan, who is investigating the killing. The mayor teams up with the police to track down the killer; to stall for time, he agrees to Scorpio's demand over Callahan's objections. During his lunch break, Harry foils a bank robbery. He shoots one robber and the getaway driver dead, and holds another at gunpoint with his Smith & Wesson Model 29 revolver, giving him an ultimatum:

I know what you're thinking: 'Did he fire six shots or only five?' Well, to tell you the truth, in all this excitement, I've kinda lost track myself. But being this is a .44 Magnum, the most powerful handgun in the world, and would blow your head clean off, you've got to ask yourself one question: 'Do I feel lucky?' Well, do you, punk?

Despite surrendering, the robber insists on knowing, and Harry jovially pulls the trigger, revealing the gun is empty.

Harry is assigned a rookie partner, Chico Gonzalez, against his opposition to working with yet another inexperienced police officer. Meanwhile, Scorpio is spotted by a police helicopter while staking for potential victims, but he escapes. Harry and Chico ride the beat, and Harry is assaulted by a neighborhood watch gang after they mistake Harry for a peeping tom. Chico comes to Harry's aid. After assisting in preventing a suicide, Harry and Gonzalez learn that Scorpio has murdered a 10-year-old African-American boy. Based on Scorpio's letter, the police think his next victim will be a Catholic priest, and set a trap for him.

Scorpio eventually arrives, kills a police officer in a shootout, and flees. The next day, the police receive another letter in which Scorpio claims to have kidnapped a teenager named Ann Mary Deacon. He threatens to kill her if he is not given a ransom of $200,000. Harry is assigned to deliver the money, wearing a radio earpiece so Gonzalez can secretly follow him. Scorpio instructs Harry via payphones around the city. They meet at the Mount Davidson cross, where Scorpio beats Harry and admits he intends to kill him and let Ann Mary die. Gonzalez intervenes and gets shot in the chest. Harry manages to stab Scorpio in the leg, but he escapes.