Orson Welles' Citizen Kane pioneered a variety of filmmaking approaches and techniques, marking it out as a landmark of cinema. In particular, Welles used overlapping dialogue, with characters talking over each other; a soundtrack of incidental and background noises; deep focus shots that placed entire shots of different depths completely into focus; and a story that unfolded in a nonlinear fashion, by using flashbacks, unreliable narrators, and contradictory facts.

Silent films, by their very nature, were unable to use dialogue or sound to convey information to the audience. While many actors were able to provide lots of content through pantomime and action, crucial elements would still be missed. Therefore, intertitles, screen shots of writing that gave dialogue or information, were used to flesh out the stories of silent films.

Casablanca, made in 1942, features a plot based around the intersection of various people who have found themselves in the eponymous Moroccan city thanks to the upheavals of World War II. Primarily focused on a romance between Humphrey Bogart's Rick and Ingrid Bergman's Ilsa, the story includes many other storylines that touch the main plot. Casablanca is often listed as among the greatest films in polls of both critics and audiences.

Alfred Hitchcock was a British director who began directing films in America in the late 1930s and became one of the most well known and popular filmakers in Hollywood for the next two decades. Among his works were Psycho, Strangers on a Train, Rear Window, and Vertigo. Raging Bull was a 1980 film directed by Martin Scorsese.

Sergio Leone was an Italian filmmaker who made his name by directing Westerns, which were originally called "Spaghetti Westerns" due to being made, performed, and produced by Italians. Leone eventually made Westerns in America, notable working with Clint Eastwood on the films A Fistful of Dollars, A Few Dollars More, and The Good, The Bad, and the Ugly. Leone helped revitalize the Western as a genre and move it into the realm of modern cinema.

The Italian filmmaker Federico Fellini was one of the most important filmmakers of the twentieth century, and his work proved highly influential around the world. Beginning in the Italian Neo-realist genre, Fellini began moving into a more surrealist and fantastical mode with his 1954 film La Strada. With 1960's La Dolce Vita, Fellini explored non-linear narrative, and with 1964's 8 1/2, Fellini began exploring dreams and fantasies in his work more explicitly.

The French New Wave was a label applied to a group of French filmmakers in the 1960s who all sought to create narrative ambiguity, a realistic shooting style, and modern stories. Among the New Wave directors were figures such as Éric Rohmer, André Bazin, François Truffaut, and Jean Luc Godard. One of their chief influences was the earlier filmmaker Jean Renoir.

The Marx Brothers, Groucho, Chico, Harpo, and Zeppo, began their career in the vaudeville era, and translated their success there into Broadway success as zany comedians. As soon as sound entered pictures, the Marx Brothers started making films, which were among the first commercially successful comedies, including 1930's Animal Crackers, 1932's Horse Feathers, and 1933's Duck Soup.

Martin Scorsese is considered one of the key figures of the "New Hollywood" movement of the 1970s, which broke from the conventions of the studio system from the 1930s-1940s. Unlike his contemporaries, Scorsese's films, including Taxi Driver, Mean Streets, and Raging Bull, were usually set in his native New York, with characters similar to the Italian and Irish working class people he grew up around.

The Godfather, based on a book by Mario Puzo, was released to great acclaim in 1972, and propelled its director Francis Ford Coppola and its stars Al Pacino, Diane Keaton, and Robert Duvall to fame. The Godfather films were all influential in moving the "gangster film" out of B-movie limbo into being considered a type of great film. The first two parts of the trilogy are considered among the greatest films of all time.