Cinema, as Jean-Luc Godard wrote, is truth 24 times a second. Documentaries both prove and disprove the point; but the truth is their strongest weapon. Here, Guardian and Observer critics pick the 10 best

No Merchandising. Editorial Use Only. No Book Cover Usage Mandatory Credit: Photo by Courtesy Everett Collection/REX (2067755a) THE MAN WITH A MOVIE CAMERA, 1929 THE MAN WITH A MOVIE CAMERA, 1929 MAN WITH A MOVIE CAMERA 1929 1920S MOVIES SILENT SPECIAL EFFECTS Film Stills Actor Personality 15739789 Photograph: Courtesy Everett Collection/REX

To best understand this 1929 silent documentary, one ought to know that its director, the exotically named "Dziga Vertov", was actually born David Abelevich Kaufman in 1896. Some say the name derives from the Russian word for spinning top, but the pseudonym is more likely an onomatopeic approximation of the sound made by the twin reels of film as the director ran them backwards and forwards through his flatbed editor. For Vertov, film was something physical, to be manipulated by man, and yet, paradoxically, he also saw it as a medium that revealed the truths of life.

Heavily influenced by futurism and constructivism, both key concerns of the Soviet avant-garde, Vertov set out with a simple plan – to record a day in the life of urban Russia. Significantly, though, there is nothing mimetic about this documentation; Vertov's plan was to make the camera and the celluloid itself as significant as the scenes portrayed. Hence the result is a heady and vertiginous piece of cinema, using optical effects, split screens and double exposures as it jump-cuts, by association, from city to city and moment to moment, the titular "man with a movie camera" more of a magician – maybe even a cyborg – than a social historian, and far from a passive bystander.

Seen now, its celebration of the burgeoning machine age is still resonant but not without humour – even if its constantly self-reflexive nature borders on exhausting (the breakneck 65-minute film has had arguably more influence on art and music than it did on cinema itself, perhaps bested in the latter regard by Dali and Bunuel's more purely surreal Un Chien Andalou, premiered later the same year). Indeed, you could draw a direct line from Vertov's film to the deadpan electronic beats of Kraftwerk, whose 1978 album Man Machine the Polish-born director would surely have relished. Damon Wise

No Merchandising. Editorial Use Only. No Book Cover Usage. Mandatory Credit: Photo by Moviestore Collection/REX (1539944a) Crumb , Robert Crumb Film and Television FILM TELEVISION CRUMB ROBERT Film Stills Personality 12064203 Photograph: Moviestore Collection/REX

The cartoonist Robert Crumb is a man who made his name by sketching gleeful and disturbing pictures of a dysfunctional USA, who is reported to masturbate over his own drawings, and who confesses to becoming sexually aroused by the sight of Bugs Bunny in drag. Terry Zwigoff's bewitching 1994 documentary, however, reveals him to be arguably the sanest brother in the most wild and wonky brood this side of the Addams family. It was Crumb's abiding good fortune to find an outlet for his demons. His other siblings were not so blessed.

Crumb (the movie) paints a portrait of the artist as snickering, self-loathing geek, pushing the boundaries of taste with his exultant inky emissions and view of modern-day America as a kind of circus of the damned. Zwigoff - Crumb's former friend turned tormentor - chases him down and shoots him at length. Having established Crumb as a successful, serious artist, the film then turns the clock back to his nightmarish upbringing in a hothouse home where he and his brothers hid from the world and drew their comics in a frenzy. Maxon Crumb would later grow up to be a sex pest, all but losing control of his motor functions as he recalls assaulting a woman in his local shop. But the film's dark centre is filled by tragic Charles, the Colonel Kurtz of American cartooning, who ventured further and further upriver while scribbling his own version of the Treasure Island tale and now lives at home with mum, strung out on anti-depressants and periodically fantasising about killing his younger brother.

Zwigoff's film is black as pitch and twisted like a pretzel. Small wonder that Crumb reacted with horror when he finally sat down to view his likeness up on screen. Xan Brooks

No Merchandising. Editorial Use Only Mandatory Credit: Photo by Everett Collection / Rex Features ( 567183a ) GREY GARDENS - Edie Beale Edith Beale 'GREY GARDENS' FILM - 1975 'GREY GARDENS' FILM 1975 GREY GARDENS EDIE BEALE STILL STILLS 317279 Photograph: Everett Collection / Rex Features

Directed by David and Albert Maysles, Grey Gardens is surely one of the most hypnotic studies of human behaviour ever recorded. For a time, its shattered-mirror assembly is really quite frustrating, offering slivers and fragments of its subjects, until suddenly it snaps from chaos into order, albeit of the most subjective kind. Made in 1975, it depicts a world now long gone, but unusually for a documentary of the period, it presents a situation that was unthinkable even then: two once-wealthy socialites living in squalor, gloom and cat shit in New York's fashionable East Hampton area.

Both women are named Edith Beale – Big Edie and Little Edie – and the film begins with the two women in their rundown house, a newspaper clipping screaming, "Mother And Daughter Ordered To Clean House Or Get Out," a second clipping telling us that the pair are Jackie Kennedy's aunt and cousin. This, however, is a much as we get in the way of third-party context: the Maysles's approach is to go inside the Beales' world and show us what they see there. It turns out to be an extraordinary vision of life through the looking glass. Artworks moulder, raccoons nibble at the once-grand 28-room mansion, and Little Edie mixes cocktails in empty mayonnaise jars. And suddenly Big Edie will drop a bombshell, saying of her daughter, "She had a proposal of marriage from Paul Getty." Turning to Little Edie, she adds, "Remember Paul? The richest man in the world?"

What Grey Gardens does quite brilliantly is to present these two wild women at face value and then reveal them as they are: thoroughbred eccentrics, by no means as crazy as they look. And though they come as double act (Big Edie shooting down her daughter with an acid tongue), Little Edie is the film's poster girl. With her strange taste in clothes, often wearing sweaters on her apparently bald head (it is never explained), Little Edie has since become an icon for gay culture and the fashion world alike: a true original. DW

Around the time he released his Man With a Movie Camera in late 1929, Vertov claimed that he had found "an authentically international absolute language of cinema," free from "foreign elements" from theatre and literature. That same year, Vertov's younger brother, the Paris-based cameraman Boris Kaufman, teamed up with novice film-maker Jean Vigo to work in the same vernacular: no scenario, no intertitles, no performers, no sets.

Vigo was the son of an anarchist-leftist who'd been strangled in prison when Vigo was 12, and immured in one of the grim boarding schools he would denigrate in his Zero de Conduite. Vigo's loathing of militarism, uniforms, clerics and authority was bred in the bone alongside an inborn subversiveness and a deeply lyrical aesthetic. A Propos de Nice is thus both scathing and exquisite. Vigo dwells at first on Nice's gilded gargoyles, the idle rich at play in this Mediterranean pleasure dome: the bourgeoisie making their evening promenade - ostensibly on parade, but recoiling at the camera's approach - buttoned-up, aloof, ugly, angry.

The other Nice edges in slowly: a filthy tramp among the rich, a child with smallpox, a cat in the garbage. Then a bizarre parade of people in huge papier-mache masks gives way to a repeated shot of pretty working-class girls dancing and flashing their drawers at the camera below them, an image of pure unharnessed hedonism and unselfconscious joy intercut with images that scorn the sombre mausoleums of generals and monarchists and blasphemously mock the tedium of a Catholic funeral procession.

The contrasts may be simple, perhaps obvious, and certainly there's venom, but it is the lyricism that lingers, and which would find its purest refinement in Vigo's third and final film, the luminous L'Atalante. John Patterson

Still from Michael Moore's Fahrenheit 9/11 (2004) Photograph: MichaelMoore.com/AP

Michael Moore's takedown of the Bush administration's reaction to the terrorist attacks on New York's World Trade Centre in September 2001 remains, by some margin, the most successful non-fiction feature to play in America – even March of the Penguins and Justin Bieber: Never Say Never don't come close. After winning the Palme d'Or from Quentin Tarantino's Cannes jury in 2004, it made the unexpected leap from arthouse to mainstream, gaining unexpected support from ordinary citizens whose spouses, sons, daughters, brother and sisters were soldiers in the field.

What's most surprising, in retrospect, is that Fahrenheit 9/11 is very much a game of two halves. The first, in which Craig Unger's book House of Bush, House of Saud is the road map, sets up lots of questions that aren't always answered, rattling the closets of George W Bush's cabinet in a bid to expose their vested and mostly lucrative interests in the war. Midway, though, the film changes tack; now the recipient of covert, digitally shot footage shot by embedded journalists, Moore is able to reveal the true miseries of the situation in Iraq, as experienced by both sides.

Viewed now, it's clear that Fahrenheit 9/11 is, in anything, a precursor of WikiLeaks and the first sign that digital technology would be a significant tool in the fight for democracy. And despite its sprawling, digressive structure, its raw and angry belief in truth and justice remains relevant today. Asked in 2009 if he still thought the film was a worthy Cannes winner, Tarantino replied: "As time has gone on, I have put that decision under a microscope and I still think we were right," he said. "That was a movie of the moment – Fahrenheit 9/11 may not play the same way now as it did then, but back then it deserved everything it got." DW

Film: The Sorrow and the Pity Dir: marcel Ophuls Date: 1970 France-Switzerland-W Germany SOURCE CREDIT - "British Film Institute" The information service of the bfi National Library may be able to carry out copyright ownership research on your behalf. Fax +44 (0) 20 7436 0165 for details of services and costs. British Film Institute 21 Stephen Street London W1T 1LN Tel +44 (0) 20 7255 1444 http://www.bfi.org.uk/ Photograph: BFI

In the late 1960s, director Marcel Ophüls was commissioned by French TV to shoot a documentary about the 1940-1944 Nazi occupation. He unearthed old sins, uncovered old witnesses and came back with a devastating 265-minute expose, a rap sheet as long as your arm and a film which exploded the myth of Vichy France as a hotbed of patriotic fervour. So troublesome were the picture's findings that it was not screened on French TV until 1981.

Weaving vibrant newsreel footage with contemporary interviews, The Sorrow and the Pity installs the town of Clermont-Ferrand as the microcosm for a cowed, craven country, presided over by the Blimpish Marshal Pétain and serenaded by the honeyed tones of Maurice Chevalier. Collaboration is the norm. A hairdresser shops her friend to the Gestapo, while a shopkeeper named Klein puts an ad in the local paper to assure customers he's not Jewish. France, it appears, was caught off guard and then sold down the river by its own middle-class. "The workers always showed more resistance," explains one old-timer. "But the bourgeoisie were scared."

In the film's second half, heroes belatedly emerge from the rubble. We are told of Gaspar, the bull-necked boss of the local Maquis, a mercurial Jewish politician who broke out of his prison cell and the faceless students from Clermont-Ferrand high school, who joined the Resistance and are no longer around to tell the tale. "Many of them have streets named after them," boasts their proud former teacher, who stood by and did nothing. XB

Nanook Of The North, film still SOURCE CREDIT - "bfi Stills" The information service of the bfi National Library may be able to carry out copyright ownership research on your behalf. Fax +44 020 7436 0165 for details of services and costs. British Film Institute 21 Stephen Street London W1T 1LN Tel +44 020 7255 1444 www.bfi.org.uk Photograph: BFI

For good or ill, Nanook of the North is the Birth of a Nation of documentary film. It cast a shadow just as dark and wide over the films in its wake, it established the grammar and syntax of the classical feature documentary at a stroke, and it exemplified all the flaws, contradictions and controversies latent in the form - observation versus intervention; objectivity or immersion; staged recreations, among many others - that would engage its practitioners for decades into the future.

Filming in the late teens of the last century, Robert Flaherty lived among the Inuit of Hudson Bay for several years after 1913. He lost his early footage in a fire and reconfigured his approach, confining himself to the story of a single hunter-fisherman. His footage still transfixes the viewer after a century: five family members and a puppy emerging from a single tiny canoe; Nanook spearing fish and harpooning seals on wild icy seas; rescuing an ice fox pup; the construction of an igloo with ice-block windows in under an hour.

Ethnographic documentary was born here ... kind of. Flaherty was not simply observing, he was recreating a way of life that was within the living memory of his subjects, but on the wane. Many Inuit now hunted with rifles, not spears, and wore modern rubber waterproofs, not sealskin. These Inuit tribesmen weren't mired in a primitive hunter-gatherer stage of life; in fact half of them were members of Flaherty's crew, including one cameraman, and Flaherty had two common-law wives during his sojourns, which you might say compromises the purity of the endeavour.

These rich and perplexing issues have been argued over by entire schools of thought in documentary, from the British in the 1930s to the cinema vérité purists of the 60s, through Jean Rouch, the Maysles brothers and Errol Morris. But it all springs from here. JP

TIMOTHY TREADWELL & BEAR Film 'GRIZZLY MAN' (2005) Directed By WERNER HERZOG 05 August 2005 SSI32120 Allstar Collection/LIONS GATE **WARNING** This photograph can only be reproduced by publications in conjunction with the promotion of the above film. A Mandatory Credit To LIONS GATE is Required. For Printed Editorial Use Only, NO online or internet use. Entertainment Orientation Landscape Sitting Film Still Documentary Animal Wearing Sunglasses BEAR Photograph: Allstar/LIONS GATE/Sportsphoto Ltd./Allstar

Werner Herzog's insistence that his documentaries are simply fiction films "in disguise" never really rang completely true until this jaw-dropping study of ill-fated adventurer Timothy Treadwell signalled the director's return from critical neglect in 2005. Although documentaries had always been an integral component of Herzog's filmography – he has the rare distinction of telling the same story twice, once as the doc Little Dieter Wants to Fly and again as the fiction movie Rescue Dawn – Grizzly Man is perhaps the director's most complete and representative genre piece: an unbelievable true-life story, explored with the director's arch, deadpan Bavarian outlook and drone.

Herzog's film is very much a documentary of its time, in which straight reportage was no longer enough and films such as Capturing the Friedmans (2003) and DiG! (2004) began drawing on the three-act structure to compose a narrative that put emotional twists and turns before straight factual revelations. Although Treadwell was only recently dead when the film debuted, Herzog puts himself square into the story, and his masterstroke is that just when Grizzly Man seems to peter out halfway through, the director goes back to the beginning: revealing the shocking truth about Treadwell, who presented himself as a wildlife expert when in fact he was anything but.

Herzog is in his element here, retracing Treadwell's steps and even listening to the recording of his death, attacked by a hungry bear as his screaming girlfriend walloped it with a frying pan ("You must never listen to this," he solemnly informs the friend who provided the tape – as if she's ever going to!). The result is the film that best represents Herzog's view of life, fiction work or otherwise. "I believe the common character of the universe is not harmony," he says at one point, "but chaos, hostility, and murder." As an alternative to Attenborough, nature has never been laid so bare. DW

The Thin Blue Line. Photograph: Ronald Grant Archive

The idea of the police as a thin blue line – a solid, unflagging protection between proper society and anarchy – is a comforting and utterly false one as depicted here, debunked over and over again as Errol Morris untangles the utterly unsafe conviction at the centre of this landmark documentary. Randall Adams, the man accused of killing a police officer in Dallas, Texas in 1976, was an itinerant worker with no motive for murder. The teenager uncovered by Morris as the likely culprit, David Harris, was a petty criminal who had bragged about the crime and went on to be convicted of another murder. How Adams was sent to death row and Harris was sent free is a story of conflicting motives and memories, of small-town biases and basic mistakes – both frustratingly specific to Adams' unlucky circumstances and telling of an entire justice system.

That The Thin Blue Line eventually led to Adams' exoneration adds a happy coda to the film, but it remains sombre and enraging at the same time. Morris recounts the story in linear, exquisite detail, using simple cuts, his signature re-enactments and even Philip Glass's hypnotic score to draw conclusions that an entire city's worth of attorneys and policemen never managed. The interviewees, rarely identified by name, are colourful glimpses into 1970s Texas: a Greek chorus who prove, without Morris ever having to say it, just how easily justice can be miscarried. An astonishing feat of reporting, The Thin Blue Line proves that facts – the presumed basis of the entire documentary genre – are as slippery and subject to manipulation as any fictional narrative. With his probing camera, Morris combines fact and fiction to suss out the truth that no one else could. Katey Rich

SHOAH [FRANCE 1985] 1980s BW FRENCH Photograph: Ronald Grant Archive

Jean-Luc Godard has often said that the greatest crime, or failure, or perhaps just the greatest "absence" in the history of cinema was the medium's inability to witness directly the central crime of the 20th century: no footage exists of the gas chambers, the ovens, the pyres of corpses burning day and night for years. In that absence, argues Claude Lanzmann, the director of Shoah, it would be obscene to imagine it or to recreate it, and over the years he has had much scorn for those who have done so, Steven Spielberg included.

When it befell him to approach the war against the Jews himself in Shoah, he forswore all archival footage, relying only on his own images of faces and places: the haunted survivors, their denial-prone camp oppressors, the bureaucrats of industrialised genocide, the Polish peasants who abetted or ignored it all, the benighted Jewish Sonderkommandos compelled to strip, shave, and incinerate the dead. All of them are intercut with the present-day sites, often reclaimed by nature, of the camps at Auschwitz, Chelmno and Treblinka, raw death seething beneath the sod, bone-fragments ten-a-penny in the loam. Publicity-shy ex-Nazis and SS officers were pinned down in full confessional flow by hidden cameras, among them while the Polish peasants seem to condemn themselves blithely out of their own mouths.

The result, at nine and a half hours, is nothing short of monumental - literally, a monument to the lost. That punishing length can be a drag on narrative velocity: all conversations - German, Polish, Yiddish - are passed through translators onscreen, and subtitled in the French that Lanzmann finally hears, but even the issue of interminability seems of a piece with the inexorable horrors being recollected.

Lanzmann had been gestating the movie all his life. He was a Jewish teenager with fake papers (like his whole family, who all survived) when he joined the resistance. After the liberation he waited an agonizing year for a single French Jew to return from Germany - pitifully few ever did. Filmed across six years and 14 countries in the mid-70s, then edited down over another four, and released to widespread acclaim in 1985, not long after Klaus Barbie was extradited to France from Bolivia, Shoah had its roots in the revitalisation of Jewish and Israeli self-consciousness and self-confidence in the aftermath of the Six Day War (celebrated in other Lanzmann docs) and the belated SS and Order Police trials in West Germany in the early 1960s. The years of mentally suppressing the ordeals of the 1940s had ended; the Kunderian war of memory against forgetting was now under way.

Hailed as a masterpiece on its release, it also generated plenty of controversy and vitriol, particularly in Poland. Many decried Lanzmann's apparent willingness to condemn the entire Polish nation (the often high-handed Lanzmann didn't deny it) without acknowledging their own extreme suffering under Nazi domination. A gargantuan attempt at historical memorialisation, Shoah stands utterly alone in documentary history. John Patterson

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