Winners include Colin Firth, Natalie Portman, Christian Bale and Melissa Leo, as 'The King's Speech' cleans up with four Oscars including the one for the best film category.
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"The King's Speech" was crowned Oscars winner on Sunday, taking three of the top Academy Award prizes at the climax of Hollywood's annual awards season.
The movie took best picture, best director and best actor for Colin Firth as a stammering King George VI, helped by an Australian voice coach to rally wartime Britain.
It also won for best original screenplay, giving the film four Oscars overall - the same as hi-tech thriller "Inception," and one more than Facebook movie "The Social Network," which had been tipped as possible best film winner.
The movie's screenwriter, David Seidler, used his acceptance speech to jokingly thank Queen Elizabeth II, among others, as well as stutterers everywhere.
"I would like to thank her majesty the queen for not putting me in the Tower of London" for putting swear words in George VI's mouth. "And I accept this on behalf of all the stutterers throughout the world.
"We have a voice, we have been heard," he said, echoing a key phrase from the movie.
"The Social Network," which had been nominated in seven Oscars categories, ended up going home with only three, and none of the major ones: film editing, original score and adapted screenplay.
"Inception," starring Leonardo DiCaprio as a hired hand who penetrates people's dreams to order, won four Oscars: cinematography, visual effects, sound mixing, sound editing.
Natalie Portman won best actress for her role in disturbing ballet thriller "Black Swan."
Boxing movie "The Fighter" already had two gongs -- best supporting actor for Christian Bale, and best supporting actress for Melissa Leo, who had both been frontrunners in their category.
Director Tom Hooper used his acceptance speech to tell the extraordinary story of how he came to make "The King's Speech" - thanks to the help of his Australian mother, who was in the audience.
"My mum in 2007 was invited by some Australian friends -- she's Australian -- in London, to a fringe theater play reading of an unproduced, unrehearsed may have called 'The King's Speech'," said the 38-year-old Brit.
He explained: "She's never been invited to a play reading her entire life before. She almost didn't go because it didn't sound exactly promising, but thank God she did.
"She rang me up after, said, Tom, I think I found your next film," he said, before addressing his mother directly, saying: "So, with this tonight, I honor you and the moral of the story is, listen to your mother."
In other prizes, "Toy Story 3," the third instalment of the family-friendly franchise starring Woody, Buzz Lightyear and co. won best animated feature Oscar as expected.
And the best foreign film prize went to "In a Better World" by Denmark's star director Susanne Bier, who vanquished movies from Algeria, Canada, Greece and Mexico.
The Oscars is the culmination of the multi-billion movie industry's awards season and has been preceded by months or frantic campaigning for the coveted gold statuettes handed out Sunday night.
Co-hosts James Franco and Anne Hathaway started the show with a filmed skit in which they were transplanted into the main films nominated for best picture, with amusing results.
Firth, who had seen as a shoo-in for best actor, made one of the typically self-deprecating acceptance speeches he has honed in winning repeated prizes at awards ceremonies over the last few months.
"I'm afraid I have to warn you that I'm experiencing stirrings, somewhere in the upper abdominals, what are threatening to form themselves into dance moves," he said.
These urges, "joyous as they may be for me... would be extremely problematic if they make it to my legs before I get off stage," he added, to laughter.
He won over Jeff Bridges -- who beat Firth to the best actor Oscar last year -- in "True Grit," Jesse Eisenberg in "The Social Network," James Franco in "127 Hours" and Spanish heart-throb Javier Bardem in "Biutiful."
Portman's rivals for best actress were veteran Annette Bening in "The Kids Are All Right," Australia's Nicole Kidman for "Rabbit Hole," Jennifer Lawrence in "Winter's Bone" and Michelle Williams in "Blue Valentine."