William Wyler (; born Willi Wyler (); July 1, 1902 – July 27, 1981) was a German-born American film director and producer. Known for his work in numerous genres over five decades, he received numerous accolades, including the most nominations for the Academy Award for Best Director (12). In addition to three Academy Awards, he also received two BAFTA Awards and one Golden Globe Award. For his oeuvre of work, Wyler was awarded the Irving G. Thalberg Memorial Award, the Directors Guild of America Lifetime Achievement Award, and the American Film Institute Life Achievement Award.

Wyler emigrated to the United States in 1921 where he worked first for Universal Studios in New York before moving to Los Angeles. By 1925, he was the youngest director at Universal, and in 1929 he directed Hell's Heroes, Universal's first sound production filmed entirely on location. Wyler went on to win the Academy Award for Best Director three times, for Mrs. Miniver (1942), The Best Years of Our Lives (1946), and Ben-Hur (1959), all of which also won for Best Picture. He was Oscar-nominated for Dodsworth (1936), Wuthering Heights (1939), The Letter (1940), The Little Foxes (1941), The Heiress (1949), Detective Story (1952), Roman Holiday (1953), Friendly Persuasion (1956), and The Collector (1965).

Film historian Ian Freer calls Wyler a "bona fide perfectionist", whose penchant for retakes and an attempt to hone every last nuance "became the stuff of legend." in Mulhouse, Alsace-Lorraine (then part of the German Empire, now France). His Swiss-born father Leopold started as a traveling salesman but later became a thriving haberdasher in Mulhouse. His mother, Melanie (née Auerbach; died February 13, 1955, Los Angeles, aged 77), was German-born, and a cousin of Carl Laemmle, founder of Universal Pictures. During Wyler's childhood, he attended a number of schools and developed a reputation as "something of a hellraiser", being expelled more than once for misbehavior. He also directed These Three (1936) with Miriam Hopkins and Merle Oberon, Dead End (1937) with Humphrey Bogart, Wuthering Heights (1939) with Laurence Olivier and Merle Oberon, The Westerner (1940) with Gary Cooper and Walter Brennan, The Little Foxes (1941) with Bette Davis, and The Best Years of Our Lives (1946) with Myrna Loy and Fredric March.

Wyler's visual style pioneered long, uncut takes in what has come to be called deep-focus cinematography - the use of lenses which can take in the entire depth of a room, keeping everything in focus, i.e. depth of field, and thus can contain dramatic changes in lighting and characters' movements in the same shot. In this, he collaborated with the pathbreaking young cinematographer of 1940's Citizen Kane, Gregg Toland. Gregg Toland shot three of the director's most celebrated films: Wuthering Heights (1939), where Toland's use of low angles, dark shadows and diffusion won him the Oscar for best cinematography; next in Lillian Hellman's adaptation of her searing stage play, The Little Foxes, into Wyler's 1941 film, which had Wyler and Toland working closely together to bring the hard-edged deep focus from Citizen Kane to bear on another tale of soul-destroying family wealth - including inventing a totally white make-up scheme for its star, Bette Davis, conveying her soullessness. Third, and most famously, is Toland's work in one of the cinematographer's last films, Wyler's heart-wrenching masterpiece, The Best Years of Our Lives (1946). This story of three American servicemen struggling to adjust to civilian life after fighting in World War 2 hit a chord with postwar audiences. Memorable examples of deep focus here include the complex scene in which the three men wind up at the same bar, unable to stay at home, and, in its powerful closing shot, a crowded family wedding disperses, leaving only two young lovers staring at one another across the expanse of an empty living room, as stunned in place, seemingly, as the camera. All three films were decorated with multiple Oscars (see the following section).

Bette Davis received three Oscar nominations for her screen work under Wyler, and won her second Oscar for her performance in Wyler's 1938 film Jezebel. She told Merv Griffin in 1972 that Wyler trained her with that film to be a "far, far better actress" than she had been. She recalled a scene that was only a bare paragraph in the script, but "without a word of dialog, Willy created a scene of power and tension. This was moviemaking on the highest plane," she said. "A scene of such suspense that I never have not marveled at the direction of it."

thumb|Olivier and Oberon in [[Wuthering Heights (1939 film)|Wuthering Heights]]

Laurence Olivier, whom Wyler directed in Wuthering Heights (1939) for his first Oscar nomination, credited Wyler with teaching him how to act for the screen, despite clashing with Wyler on multiple occasions. Olivier would go on to hold the record for the most nominations in the Best Actor category at nine, tied with Spencer Tracy. Critic Frank S. Nugent wrote in The New York Times: "William Wyler has directed it magnificently. It is, unquestionably, one of the most distinguished pictures of the year."

In 1950, Wyler and Olivier made a second film together, Carrie, which was not a commercial success. However, some critics state that it nonetheless contains Olivier's finest film performance, but because of its old-fashioned story, the film was very under-appreciated: In critic Michael Billington's opinion: