Colin Firth as stammering British ruler George VI in "The King's Speech" earned the best-actor prize, while Natalie Portman won best actress as a delusional ballerina in "Black Swan."
The boxing drama "The Fighter" captured both supporting-acting honors, for Christian Bale as a boxer-turned-drug-abuser and Melissa Leo as a boxing clan's domineering matriarch.
"The King's Speech" also won the directing prize for Tom Hooper and the original-screenplay Oscar for David Seidler, a boyhood stutterer himself.
"I have a feeling my career has just peaked," Firth said. "I'm afraid I have to warn you that I'm experiencing stirrings somewhere in the upper abdominals which are threatening to form themselves into dance moves."
Among those Portman beat was Annette Bening for "The Kids Are All Right." Bening now has lost all four times she's been nominated.
"Thank you so much. This is insane, and I truly, sincerely wish that the prize tonight was to get to work with my fellow nominees. I'm so in awe of you," Portman said.
Network censors bleeped Leo for dropping the F-word during her speech. Backstage, she jokingly conceded it was "probably a very inappropriate place to use that particular word."
"Those words, I apologize to anyone that they offend. There is a great deal of the English language that is in my vernacular," Leo said.
Bale joked that he was keeping his language clean. "I'm not going to drop the F-bomb like she did," he said. "I've done that plenty of times before."
But the Oscars, being a global affair, were telecast elsewhere in the world with Leo's words uncensored. Viewers who watched the show on Star Movies, a major channel available throughout Asia, heard the F-word loud and clear.
The best-picture win for "The King's Speech" was the first for its distributor, the Weinstein Co., founded by savvy awards campaigner Harvey Weinstein and his brother Bob after they left Miramax, their old outfit. At Miramax, Weinstein oversaw best-picture wins for "Chicago," "Shakespeare in Love" and "The English Patient."
"The King's Speech" had been the heir-apparent for Hollywood's highest honor since late January, when it seized the awards momentum with a leading 12 Oscar nominations and a sweep of top prizes from influential actors, directors and producers guilds.
Before that, the Facebook drama "The Social Network" had looked like the front-runner, dominating awards from key critics' groups and winning best drama at the Golden Globes. An of-the-moment tale such "The Social Network" would have fit the Oscars' recent pattern, with contemporary stories such as "The Hurt Locker," "Slumdog Millionaire" and "Crash" winning best picture.
But Oscar voters reverted to history, pomp and tradition this time, qualities that marked such past best-picture winners as "The Last Emperor," "A Man for All Seasons" and "Lawrence of Arabia."
Those films were epic in scope, while "The King's Speech" is a deeply personal tale, chronicling the unlikely kinship between George VI and unconventional speech therapist Lionel Logue (Geoffrey Rush), who helped the king bring his stammer under control.
Hooper, a relative big-screen newcomer best known for classy TV drama, took the industry's top filmmaking prize over Hollywood veteran David Fincher, who had been a strong prospect for "The Social Network."
The prize was presented by last year's winner, Kathryn Bigelow, the first woman to earn a directing Oscar.
"Thank you to my wonderful actors, the triangle of man love which is Colin Firth, Geoffrey Rush and me. I'm only here because of you guys," Hooper said.
Firth's win seemed inevitable from the time "The King's Speech" premiered at film festivals late last summer. Perhaps sealing the deal for Firth was the fresh memory of his dazzling performance in "A Single Man," which earned him a best-actor slot a year ago, his first Oscar nomination in a career that includes a diverse mix of sober drama ("Girl With a Pearl Earring," "Where the Truth Lies") and popular romps ("Mamma Mia!" and the "Bridget Jones" movies).
Portman's role as a dancer losing her grip on reality while preparing to star in "Swan Lake" has been particularly fertile for the actress: She met her fiance, choreographer Benjamin Millepied, on the set of "Black Swan," and she is pregnant with their first child.
A former child star who made a memorable feature-film debut in 1994's hit man tale "The Professional," Portman grew up on screen, starring in her teens and early 20s as the tragedy-bound spouse of future evil overlord Darth Vader in George Lucas' second "Star Wars" trilogy and gracefully moving into adult roles, including 2004's "Closer," which brought her first Oscar nomination.
Leo's win capped an unusual career surge in middle age for the 50-year-old actress, who had moderate success on TV's "Homicide: Life on the Street" in her 30s but leaped to big-screen stardom in her late 40s, a time when most actresses find good roles hard to come by.
In disbelief when she took the stage, Leo said, "Pinch me."
Hollywood legend Kirk Douglas, who presented her award, obliged with a little pinch on her arm.
Bale earned the same prize his Batman co-star, the late Heath Ledger, received posthumously two years ago for "The Dark Knight." At the time, Bale had fondly recalled a bit of professional envy as he watched Ledger perform on set like a whirlwind as the diabolical Joker while the film's star had to remain clenched up as the stoic, tightly wound Batman.
"The Fighter" gave Bale his turn to unleash some demons as Dicky Eklund, a boxer whose career unraveled amid crime and drug abuse. Bale delivers a showy performance full of tics and tremors, bobbing and weaving around the movie's star and producer, Mark Wahlberg, who plays Eklund's stolid brother, boxer Micky Ward.
The screenplay win realized a lifelong dream for "King's Speech" writer Seidler, a boyhood stutterer born in London in 1937, a year after George took the throne. Seidler, who overcame his own stutter at age 16, had long vowed to one day write about the monarch whose fortitude set an example for him in childhood.
Seidler thanked Queen Elizabeth II, daughter of King George, "for not putting me in the Tower of London for using the Melissa Leo F-word." The film includes two scenes where the king spouts profanity in anger to help force out his syllables.
The Oscar for adapted screenplay went to Aaron Sorkin for "The Social Network," a chronicle of the birth of Facebook based on Ben Mezrich's book "The Accidental Billionaires." "The Social Network" also won for musical score for Trent Reznor and Atticus Ross, and for film editing.
The sci-fi blockbuster "Inception" tied "The Kings Speech" with four Oscars, all in technical categories: visual effects, cinematography, sound editing and sound mixing.
"Inside Job," an exploration of the 2008 economic meltdown, won for best documentary, which proved an uncommonly lively category this time.
The Oscar buildup featured speculation about whether Banksy, a mystery man of the street-art world, might show up for his awards entry, "Exit Through the Gift Shop." If he was at the Oscars, he did not declare himself.
But it was the topic on most people's minds the last two years, the economy, that resonated among Oscar voters. "Inside Job" director Charles Ferguson subjected Wall Street players, economists and bureaucrats to a fierce cross-examination to depict the economic crisis as a colossal crime perpetrated on the working-class masses by a greedy few.
"Forgive me, I must start by pointing out that three years after our horrific financial crisis caused by financial fraud, not a single financial executive has gone to jail, and that's wrong," Ferguson said.
"Toy Story 3," last year's top-grossing release, won the fourth-straight animated-feature Oscar for Disney's Pixar Animation unit. Pixar has produced six of the 10 Oscar recipients for animation since the category was added, including "Finding Nemo," "WALL-E" and last year's winner, "Up."
It was an odd backdrop for a Pixar win, the Oscar ceremony using visual effects to present the award in front of a re-creation of Far Far Away, the fairy-tale realm of Disney rival DreamWorks Animation's "Shrek" movies. The original "Shrek" won the first Oscar for feature animation, but unlike the durable "Toy Story" franchise, the "Shrek" series finished with a critical dud, last year's "Shrek Forever After."
"Toy Story 3" also won an Oscar for Randy Newman's theme tune, "We Belong Together." Newman, who had been a steady Oscar loser for years, now has two Academy Awards, previously winning for the theme song of another Pixar film, "Monsters, Inc."
The show opened with co-hosts Anne Hathaway and James Franco inserted into a montage of scenes from best-picture nominees, built as a series of dream sequences reminiscent of "Inception." The footage included such guests as Morgan Freeman and last year's Oscar co-host Alec Baldwin.
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