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'Mork & Mindy' (1978-82)
Robin Williams was an unknown stand-up comedian when Garry Marshall cast him as the alien manchild from Planet Ork on an episode of Happy Days, a guest spot that quickly transformed into a spin-off (not to mention a 1979 Golden Globe win and Emmy nomination). It's the first great demonstration of Williams' utterly unique blend of childlike enthusiasm and aggressive absurdity—not to mention his gift for spouting a Zeitgeist-defining catchphrase. Na-Nu Na-Nu!
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The World According to Garp (1982)
And now for something completely different: Fresh off Mork's cancellation, Williams played the all-too-human title character in this John Irving dramedy. We watch as Garp ages from randy high schooler to troubled family man, his life juxtaposed against the mad days of the '60s counterculture. It's a coming of age story, really, with Williams as a believably confused, oddly endearing everyman.
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Good Morning Vietnam (1987)
Williams' golden period began with this loose biopic of Vietnam DJ Adrian Cronauer. Most of the broadcast scenes—replete with raucously tangential jokes-within-jokes and Rod Serling impressions—were Williams' motor-mouthed improvisations. A nexus point for Williams the Comedian and Williams the Thespian—and his first of three Best Actor Oscar nominations.
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Dead Poets Society (1989)
John Keating quotes Whitman, he demands his students stand up on their desks, he whispers ''seize the day'': A quarter century later, is there a silver-screen teacher more iconic? In his later work, Williams could hit the ''inspirational'' note a little too hard, but here he's the perfect mix of light whimsy and professorial gravitas.
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The Fisher King (1991)
Williams was often at his best in projects that met his loopy sensibility. So it's only natural that madman-auteur Terry Gilliam proved an ideal collaborator. Williams earned his third Best Actor nom in four years playing the homeless, Quixote-esque Henry Sagan, whose lunatic mock-heroism represses almost unbearable tragedy. It's over-the-top, but with an undercurrent of genuine sadness.
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It's hard to think of a single sentence uttered (and often improvised) by Williams in the Disney film that didn't become etched in the brains of a generation of '90s children. As the Genie (a role that won him a special Golden Globe for his vocal work), Williams defined a particular genre of kid-friendly, hyper-referential comedy, practically inventing every animated movie of the last couple decades on the spot.
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Mrs. Doubtfire (1993)
The highest-grossing movie of 1993 was a blockbuster digital-effects epic about gigantic man-eating dinosaurs. And the second highest-grossing movie of 1993 was a comedy about a man who pretends to be a funny old British lady. The climactic restaurant scene—with Williams swapping characters and accents during frequent trips to the bathroom—might just be Williams' pinnacle.
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The Birdcage (1996)
In Mike Nichols' sweetly tart comedy-of-postmodern-manners, Williams is actually the most restrained member of the ensemble. Ceding the scenery-chewing (and the cross-dressing) to onscreen partner Nathan Lane, Williams plays club owner Armand Goldman with a wry, gentle good humor.
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Good Will Hunting (1997)
The scenes between Williams' therapist Dr. Sean Maguire and Matt Damon's titular troubled savant crackle with unabashed emotion that goes beyond simple feel-goodery, and for this, he finally won an Oscar. If you've forgotten why, grab some tissues and google ''It's not your fault.''
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One Hour Photo (2002)
Quickly on the heels of the underappreciated Insomnia and Death to Smoochy, Williams hit a new dramatic peak playing a lonely and obsessive photo-counter drone Sy Parrish, a role that's seemingly the inversion of his entire career. You don't sit back and watch Sy go—you agonizingly wait for him to erupt.
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The Night at the Museum series (2006?14)
Portraying the 26th President of the United States as a chipper parody of alpha-maledom, the actor's Teddy Roosevelt is a goofily endearing tour guide. In a film series chock-full of digital effects, none were more special than the wild bravado of a fully-engaged Williams.