Night and Fog (1955)
Director Alain Resnais's film was "one of the first … to deal in a forthright way with a now-conventional theme in documentary, the Nazi concentration camps," says Jonathan Kahana, assistant professor of cinema studies for Tisch School of the Arts at New York University. "It is still shocking in its use of experimental techniques, including the combination of present-day color and past-tense black-and-white footage, [and] its expressive musical score." Adds Renov: Though the film is more than 50 years old, "it still has a stinger in its tail that doesn't go away."

The Thin Blue Line (1988)
Director Errol Morris's "gripping investigation of murder and injustice, set to a Philip Glass score, has as much story and style as 10 films noir," says Kahana. "Its ­often-­imitated, never-duplicated use of color, close-ups, interviews, and reenactments changed the look and form of documentary forever." Adds Harris: "He recognizes the fact that audiences no longer will accept statements as a given or as instantly believable just because they're shown in a documentary film - that we all have some level of skepticism and that we ought to have some level of skepticism."

Harlan County, U.S.A. (1976) and
American Dream (1991)
Barbara Kopple gathered a pair of Oscars for her documentaries about miners and meatpackers. The films "make an epic double bill on the rise and fall of the labor movement in America," says Kahana. "Kopple is the epitome of the committed filmmaker, rolling up her sleeves and joining the fray, helping out on the picket lines, and getting shot at by vigilantes."

Nobody's Business (1996)