Daniel Day-Lewis has made Oscar history - becoming the first man to be named best actor three times.
The recognition for his performance in the title role of Steven Spielberg's biopic of former US president Abraham Lincoln puts him above Hollywood legends including Dustin Hoffman and Marlon Brando, who both won it twice.
Accepting his award from Meryl Streep, Day-Lewis told the audience: "I really don't know how any of this happened."
Day-Lewis also paid tribute to his wife, before tearfully thanking his mother.
The other big winners on the night were Anne Hathaway, named best supporting actress for her role in Les Miserables, Jennifer Lawrence who won best actress and Ben Affleck's Argo, which won best film. Lawrence, who stumbled on her way to the stage, said: "You guys are just standing up because you feel bad that I fell over and that's embarrassing. This is nuts."
Ang Lee was named best director for Life Of Pi, while Adele triumphed in the best original song category for her Bond theme Skyfall. Earlier she had performed the song on stage at the Dolby Theatre in Hollywood - the first time she had ever sung it live.
There were also wins for Quentin Tarantino's western Django Unchained with Christoph Waltz named best supporting actor, while Tarantino picked up the Oscar for original screenplay, telling his fellow writers: "You guys are so wonderful. Peace out."
The nominees for best film were introduced by first lady Michelle Obama from the White House. Director and star Affleck paid tribute to the "genius" of Spielberg, whose film Lincoln was one of the ones that lost out. Referring to his early success with the Oscar-winning Good Will Hunting, he said: "I never thought I would be back here and I am because of so many of you who are here tonight." He added: "It doesn't matter how you get knocked down in life, all that matters is that you get up."
The award for best animated short film went to Disney's Paperman, meaning National Film and Television School students Fodhla Cronin O'Reilly and Timothy Reckart missed out on an Oscar.
Halle Berry - a one-time Bond girl - introduced a tribute to the Bond films and music made up of classic clips of 007's adventures which continued with Dame Shirley Bassey singing the theme to the 1964 film Goldfinger which was given a standing ovation from the assembled stars.