Gangster Squad is a 2013 American action thriller film directed by Ruben Fleischer and written by Will Beall, based on a non-fiction book by Paul Lieberman. The film stars Josh Brolin, Ryan Gosling, Nick Nolte, Emma Stone, Anthony Mackie, Giovanni Ribisi, Robert Patrick, Michael Peña and Sean Penn. Set in 1949, a group of real-life LAPD officers and detectives called the Gangster Squad are assigned to bring down crime kingpin Mickey Cohen.

After the script spent several years on the Black List, production began in September 2011 around Los Angeles, lasting through December. The film was originally set to be theatrically released September 7, 2012, but in the wake of the 2012 Aurora, Colorado, shooting, Warner Bros. pushed it back to a January 11, 2013, release to accommodate re-shoots, which took place in August 2012.

Gangster Squad received mixed reviews from critics, where it grossed $105 million worldwide.

In 1949 Los Angeles, crime boss Mickey Cohen has become the most powerful figure in the California criminal underworld and intends to expand his criminal enterprise to encompass the entire West Coast. The LAPD has not been able to stop his ruthless rise, as he has eliminated witnesses, hired dirty cops to protect his activities, and avoided prosecution through corruption in the justice system.

Determined to put a stop to Cohen, LAPD Chief Bill Parker creates a secret police unit tasked with dismantling Cohen's enterprise. The unit, composed of officers who do not carry badges and are authorized to act outside of the law, are led by the skilled World War II OSS veteran Sergeant John O'Mara. With the help of his wife, Connie, he recruits fellow war veteran Detective Jerry Wooters and four incorruptible misfit officers: knife-wielding Lieutenant Coleman Harris, wire tapping expert and family man Conwell Keeler, outlaw sharpshooter Max Kennard, and Kennard's rookie protégé Navidad Ramirez.

Despite initial setbacks, such as a casino raid thwarted by corrupt Burbank police officers, the Squad strikes several successful blows at the heart of Cohen's operations, including shutting down his lucrative wire gambling business. They break into Cohen's mansion and Keeler plants a bug in the back of a television. As a result, Cohen believes someone has betrayed him and lashes out at those around him, including his etiquette tutor Grace Faraday. Wooters and Faraday have entered into a secret romantic relationship, and he tries to help her escape from Cohen, enlisting the help of mutual friend and gangster Jack Whalen.

Realizing the attackers have never stolen his money, Cohen deduces they are cops and realizes that they have bugged his house. He uses it to lure the Squad into an unsuccessful ambush in Chinatown while Keeler is executed by a hitman. When Faraday witnesses Cohen murder Whalen, she agrees to testify against her former employer. O'Mara forces the crooked Judge Carter to sign an arrest warrant before leading the Squad to the Park Plaza Hotel to arrest Cohen.

Cohen and his men engage in a lengthy shootout with the Squad, during which Wooters and Kennard are wounded. Cohen and his bodyguard Karl Lennox escape, but O'Mara rams their vehicle into a fountain. Navidad helps a dying Kennard shoot Lennox, saving O'Mara. Cohen and O'Mara fight each other in a brutal bareknuckle brawl while onlookers and journalists gather. O'Mara finally beats Cohen and has him arrested, ending his reign over Los Angeles.

The film explains that the Gangster Squad has never been mentioned for its role in keeping the Mafia from gaining a foothold in L.A., and that its surviving members remain secret. Cohen is sentenced to life imprisonment at Alcatraz, and is greeted with a lead-pipe beating by inmates who were friends of Whalen. Harris and Ramirez partner together to walk the beat, Wooters and Faraday continue their relationship, and O'Mara quits his job with the LAPD to live a quiet life with his wife and newborn son.

Although the film is inspired by the real-life LAPD Gangster Squad, much of it is fabricated.^[30][31]

• The film portrays Cohen organizing the murder of his predecessor Jack Dragna. In reality, Cohen largely sidelined Dragna as head of the Los Angeles crime family but otherwise left him alone; Dragna died of a heart attack in 1956.
• The film shows Cohen's primary business as gambling, with prostitution and drug dealing as sidelines. In reality, Cohen's main racket was bookmaking; he detested drugs.
• William Parker was only 45 in 1949, not in his 70s like Nick Nolte (Parker died at age 61 in 1966). He also did not create the Gangster Squad; it was created by Chief Clemence B. Horrall in 1946, and was largely an effort to improve the city's image, regardless of whether it actually pursued criminals.
• The film concludes with Cohen being arrested in 1949 for murder and sent to Alcatraz. In reality, he was imprisoned in 1951 and again in 1961 for tax evasion. He was, however, attacked with a lead pipe while in prison, as depicted in the film.
• While Anthony Mackie and Michael Peña are members of the film's Squad, the real Squad was entirely Caucasian.
• While it is possible Cohen murdered Jack Whalen in real life, it was not at Whalen's home as depicted in the film. Whalen was shot in 1959 while at dinner with Cohen and three of his associates, and Cohen was not officially accused of it.
• Cohen's bodyguard Johnny Stompanato was not shot as depicted in the film, but lived until 1958, when he was stabbed by Cheryl Crane, the daughter of his girlfriend Lana Turner.
• The character of Max Kennard was based on real life lawman Doug "Jumbo" Kennard, who died after crashing his car as he drove under the influence of alcohol. He had already retired, and was not shot in the line of duty as in the film.
• In the film, Conwell Keeler is the first member of the Squad to be killed. In real life, he outlived all of the Squad's other members, dying of a stroke in 2012.