Daniel Day-Lewis has won the Oscar for best actor on an evening when all the major acting prizes went to European actors.
Day-Lewis picked up the award for his role in There Will Be Blood, meanwhile the Coen Brothers' film No Country For Old Men walked away with four Oscars.
Joel and Ethan Coen were jointly awarded best director and the film won best picture.
Javier Bardem won also best supporting actor for his role as a hitman in the Coen brothers' dark comedy.
British actress Tilda Swinton won best supporting actress for her performance in Michael Clayton and gave the most entertaining speech of the evening, making fun of co-star George Clooney.
"Seeing you climb into that rubber suit from Batman and Robin, the one with the nipples, every morning under your costume, on the set, off the set, hanging upside-down at lunch . You rock man," she said.
Completing the European sweep of the acting awards, France's Marion Cotillard followed up her BAFTA success by earning the best actress prize for La Vie En Rose.
"I'm speechless now. Thank you life; thank you love. It is true there are some angels in this city," she said in an emotional acceptance speech.
After receiving his Oscar from last year's best actress Dame Helen Mirren, Day-Lewis joked it was "the closest I'll ever come to getting a knighthood".
The ceremony, the 80th anniversary of the Academy Awards, had been put together in just a couple of weeks after the writers' strike threatened to cancel the whole event.
Host Jon Stewart expressed his relief the dispute was now over: "These past three and a half month have been very tough. The town was torn apart by a bitter writers' strike.
"But I'm happy to say that the fight is over," he said.
The evening's biggest winner, No Country For Old Men had long been a favourite to do well.
In collecting the joint best director Oscar, Joel Coen thanked Hollywood saying: "We're very thankful to all of you out there for continuing to let us play in our corner of the sandbox."
The successful night for European cinema included the best song Oscar going to Falling Slowly from the Irish film Once, starring Glen Hansard and Marketa Irglova.