Mafia films—a version of gangster films—are a subgenre of crime films dealing with organized crime, often specifically with Mafia organizations. Especially in early mob films, there is considerable overlap with film noir. Popular regional variations of the genre include Italian Poliziotteschi, Chinese Triad films, Japanese Yakuza films, and Indian Mumbai underworld films.

The American movie The Black Hand (1906) is thought to be the earliest surviving gangster film. In 1912, D. W. Griffith directed The Musketeers of Pig Alley, a short drama film about crime on the streets of New York City (filmed, however, at Fort Lee, New Jersey) rumored to have included real gangsters as extras. Critics have also cited Regeneration (1915) as an early crime film.

Though mob films had their roots in such silent films, the genre in its most durable form was defined in the early 1930s. It owed its innovations to the social and economic instability occasioned by the Great Depression, which galvanized the organized crime subculture in the United States. The failure of honest hard work and careful investment to ensure financial security led to the circumstances reflected in the explosion of mob films in Hollywood and to their immense popularity in a society disillusioned with the American way of life.

The years 1931 and 1932 saw the genre produce three enduring classics: Warner Bros.' Little Caesar and The Public Enemy, which made screen icons out of Edward G. Robinson and James Cagney, respectively, and Howard Hawks' Scarface starring Paul Muni, which offered a dark psychological analysis of a fictionalized Al Capone and launched the film career of George Raft. These films chronicle the quick rise, and equally quick downfall, of three young, violent criminals, and represent the genre in its purest form before moral pressure would force it to change. Though the gangster in each film would face a violent downfall which was designed to remind the viewers of the consequences of crime, audiences were often able to identify with the charismatic anti-hero. Those suffering from the Depression were able to relate to the gangster character who worked hard to earn his place and success in the world, only to have it all taken away from him.

Because of the Production Code, such films had to always end with the gangster protagonist dying in a hail of bullets at the film's climax. Furthermore, the film's protagonist was always somehow "deviant" from the norms of American society. In Little Caesar, it is strongly implied that Caesar Enrico Bandello (Edward G. Robinson) is gay as he is clearly jealous when his handsome friend Joe Massaria (Douglas Fairbanks Jr) dances seductively with his lover Olga (Glenda Farrell), which causes him to make his first major mistake that leads to his downfall. In The Public Enemy, the protagonist Tom Powers (James Cagney) is a casually brutal misogynist, most notably expressed in the famous scene when he rammed a grapefruit into the face of his girlfriend after she annoys him. About this scene and many others similar to it, the American critic Thomas Doherty noted "what went largely unremarked was the vicious nature of the relationships between men and women in the gangster genre". In Scarface, Tony Carmonte (Paul Muni) has a barely veiled incestuous passion for his sister Cesca (Ann Dvorak), which leads to his death.

Despite the genre spanning the decade before dying out, some argue that the gangster film in its purest form only existed until 1933, when restrictions from the Production Code led to films that did not have the same power as the earlier ones.

As the appeal and attraction of gangster movie stars such as Cagney, Robinson, Muni, and Raft grew, so too did the efforts to combat their fascination. During the early years of crime film, Scarface, arguably the most violent of gangster films created during the entire decade, particularly was the subject of criticism. Released in 1932, it ushered in the worst year of the Depression, and as profits slid, Hollywood did what it could to restore its earnings, which resulted in the upping of sex and violence in the movies. Scarface can be interpreted as a representation of the American dream gone awry, presented when US capitalism had reached its lowest, and Prohibition was being seen as a failed social experiment and would soon be abolished. It faced opposition from regulators of the Production Code, and its release was delayed for over a year while Hawks attempted to tone down the incestuous overtones of the relationship between Paul Muni's character Tony Camonte and his sister (Ann Dvorak).

The Capone-like Carmote is in many ways the most monstrous gangster portrayed in 1930s films, a man utterly devoid of any positive qualities as he ruthlessly schemes and shoots his way to the top. Through Carmote was closely based on Al Capone, the most notable aspect of his character, namely his "incestuous obsession" with his sister and the way he kills any man who expresses any sort of interest in her as he wants her for himself, was not based on Capone. Besides for Capone, there are many references to The Great Gatsby in Scarface such as the scene where Carmonte lovingly caresses his silk shirts, which like the same scene in The Great Gatsby are a sign of material success for the protagonist. The Great Gatsby was the best-selling novel of 1925, and the references to the novel in the film were meant to symbolize the decay of America from the hopeful days of 1925 to the sense of collapse of 1932. The violence and the barely veiled theme of incestuous passion greatly outraged critics, churches, politicians and civic groups in 1932. The journalist Jack Alicoate in the Film Daily wrote that watching Scarface induced "nausea" in him and that "There are certain things that simply do not belong on the screen. The subject matter of Scarface is one of them".