If one were to compile a litany of the greatest American screen actors of all time, they would be hard-pressed not to include Robert Duvall. The highly acclaimed actor made his big-screen debut in 1965 and would go on to star in some of the most critically and commercially successful films ever made, including The Godfather films.

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In 1983, Duvall won his one and only Academy Award for Best Actor in a Leading Role following his soulful turn in Tender Mercies, in which he played a faded country singer attempting to piece his life back together. With two upcoming projects at age 90 (Hustle, The Ploughmen), Duvall shows no signs of slowing down anytime soon.

M.A.S.H. (1970) - 7.5

Robert Duvall in M.A.S.H. looks at someone off camera in the shadows.

Five years after his screen debut, Duvall caught the eye of director Robert Altman for the role of Major Frank Burns in M.A.S.H., the classic and irreverent war comedy that launched the career of several '70s film stars. The story tracks the sophomoric shenanigans of a mobile army medical staff during the Korean War.

As Major Burns, Duvall plays the main antagonist in the film who hilariously tries to quell the medical staff's frivolous hard-partying ways with his stern discipline and fervent religious prayer. Duvall plays the part with deadpan austerity, which only makes the role funnier.

The Natural (1984) - 7.5

Robert Duvall in The Natural in a cap and bow tie as he stares through a wire fence.

Barry Levinson's The Natural is a mythical baseball movie about Roy Hobbs (Robert Redford), a star player whose magical baseball bat turns him into a godlike figure on the field. However, without the help of wily sportswriter Max Mercy (Duvall), his career would have languished in obscurity.

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As a rousing feel-good family sports film, The Natural succeeds on nearly every level. The timeless fairytale quality of the story and supernatural element to Roy's "Wonderboy" bat is truly inspiring, with Duvall and Redford showing tremendous chemistry onscreen together.

Thank You For Smoking (2005) - 7.6

Nick and The Captain share a limo in Thank You For Smoking

Duvall lends his hefty onscreen gravitas as the villainous Captain, founder of the Academy of Tobacco Studies lobby group in Thank You For Smoking. The scathing dark comedy movie from director Jason Reitman toys with the audience's sympathy, as the main character, Nick Naylor (Aaron Eckhart), heads the pro-tobacco organization.

The film gets to the heart of public perception, corporate spin, and the complex legal system relating to free speech in marketing, and does so with a light touch and cynical tone that remains entertaining throughout. Despite having just a few scenes, Duvall's imposing presence makes a lasting impression.

Falling Down (1993) - 7.6

Prendergast shows his badge in Falling Down

Joel Schumacher's Falling Down remains an underrated movie about isolation and alienation reaching an emotional and physical breaking point. Duvall plays LAPD Sergeant Prendergast, a detective on his last day of work who reluctantly tracks a rogue defense contractor (Michael Douglas) who snaps and goes on a violent rampage after witnessing societal decay.

While Douglas has the flashier role, Duvall grounds the material by giving a subtle, humorous, and well-observed turn as a by-the-book lawman at the end of his rope who must weigh his desire to retire with the importance of making one final arrest. More than the performances, what the movie says about the crumbling nature of society is truly special.

The Conversation (1974) - 7.8

The Director sits at his desk with back turned in The Conversation

Although he has an uncredited cameo as The Director, Duvall's onscreen importance in Francis Ford Coppola's The Conversation remains key to how the plot functions. The story tracks Harry Caul (Gene Hackman), a skeptical surveillance expert who gets entangled in a conspiracy when he thinks he overhears an assassination plot.

In a fascinating glimpse of fear, paranoia, mistrust, and the psychological ramifications of such, The Conversation is Coppola at his most personal. The captivating character study was made in between the first two Godfather films, with Duvall stepping in and deliver a powerful expository scene in the final act that shakes the entire story up.

Sling Blade (1996) - 8.0

Karl's father sits in his living room chair in Sling Blade

Duvall gives a masterclass in subtle screen acting in Sling Blade, Billy Bob Thornton's emotionally shattering tale of unthinkable abuse. The story of Karl Childers (Thornton) and the profoundly moving bond he makes with 12-year-old Frank (Lucas Black) proves that Karl is a far better father figure than his own.

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When Karl finally pays a visit to his unnamed father at the end of the film, the audience has a much firmer understanding of how Karl was raised, why he grew up with such little love, and how his life was steered in the wrong direction by his so-called loved ones. Sling Blade is one of the most emotionally devastating movies of the last 25 years, thanks in large part to Duvall's memorable presence.

Network (1976) - 8.1

Frank holds a newspaper and points a finger in Network

Currently rated #217 on IMDb's Top 250, Sidney Lumet's Network is one of the most important and prophetic films of the 1970s. The story concerns a TV network willing to do anything to secure high ratings, including exploiting the nervous breakdown of a news anchor who suddenly grows a conscience and begins telling the unfiltered truth.

The four-time Oscar-winning film stars Duvall as Frank Hackett, a powerful TV executive who agrees to let the ranting news anchor have his own news program. Far ahead of its time, what the movie says about corporate greed, news versus entertainment, reality television, and the societal degradation they all lead couldn't be more prescient.

Apocalypse Now (1979) - 8.4

Kilgore points at waves in Apocalypse Now

Duvall earned the second Oscar nod of his illustrious career for his role as Colonel Kilgore in Apocalypse Now, a hilariously casual surfing enthusiast who would ready study breaking swells than concern himself with bombs detonating at his feet. His line "I love the smell of napalm in the morning" is among the greatest movie lines in history.

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Francis Ford Coppola's epic Vietnam War film won two Oscars and is currently rated #53 on IMDb's Top 250. While the troubled development and production of Apocalypse Now is almost as infamous as the movie itself, Duvall gets to showcase his rare comedic talent that perfectly encapsulates how ridiculously absurd the Vietnam War was from the start.

The Godfather: Part II (1974) - 9.0

Tom and Michael smoke at Senate hearing in The Godfather Part II

According to IMDb, Duvall belongs to the second and third highest-rated movies of all time. While many consider The Godfather: Part II superior to the original, the second leg of Coppola's trilogy sees Tom Hagen (Duvall) get a temporary boost to acting Don under Michael's leadership.

By appointing Tom to such an esteemed role, Michael expresses his implicit trust in him as a loyal family member, despite being a non-blood relative. Duvall comports himself with such a sophisticated air of elegance as a morally stricken white-collar criminal who must play both sides of the law.

The Godfather (1972) - 9.2

Tom leans over table to talk business in The Godfather

Duvall earned his first Oscar nod for his role as Tom Hagen in The Godfather, the Corleone family consigliere and shrewd legal rep. In many ways, Tom has the most complicated role of anyone in the Corleone family other than Michael. As Vito's non-Italian adoptive son, he remains loyal, despite failing to truly understand the blood ties that make the Italian mafia so formidable.

On the other hand, Tom knows precisely what Vito, Michael, and Sonny are up to behind the scenes, making him a vital character in ensuring their safety from the law. Without Hagen, the Corleone family would not have lasted as long as it did. Without Duvall, The Godfather would not be nearly as strong.

NEXT: The Godfather - 10 Most Iconic Locations