Daniel Day-Lewis has rewritten Oscars history by becoming the first man to win the Best Actor trophy three times.
The British-born actor received his award for his portrayal of Abraham Lincoln in the Steven Spielberg film Lincoln.
He was previously awarded the best actor Oscar for his roles in My Left Foot and There Will Be Blood.
Daniel Day-Lewis is the first man in history to collect three Best Actor trophies
"I really don't know how any of this happened. I do know that I have received more than my share of good fortune," he said while accepting the award.
Day-Lewis also paid tribute to his wife, before tearfully thanking his mother.
Day-Lewis's win came at the expense of Bradley Cooper (Silver Linings Playbook), Hugh Jackman (Les Miserables), Joaquin Phoenix (The Master) and Denzel Washington (Flight).
The 55-year-old also won Best Actor awards at the Golden Globes, Screen Actors Guild and BAFTAs.
Marlon Brando, Gary Cooper, Tom Hanks, Dustin Hoffman, Fredric March, Jack Nicholson, Sean Penn and Spencer Tracy have all won two Best Actor awards.
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.
Adele won best original song category for her Bond theme Skyfall
Ang Lee was named best director for Life Of Pi, while Adele triumphed in the best original song category for her Bond theme Skyfall.
She thanked her songwriting partner Paul Epworth, who came on stage with her, for "believing in me all the time, and my man, I love you baby".
Earlier she had performed the song on stage at the Dolby Theatre in Hollywood - the first time she had ever sung it live.
Christopher Plummer presented the Oscar for best supporting actress to Hathaway.
Referring to her character Fantine, who was forced into prostitution, an emotional Hathaway said she hoped for a future in which "the misfortunes of Fantine will only be found in stories and nevermore in real life".
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."
Daniel Day-Lewis With His Three Oscars
Oscars 2013: Inside The Awards Ceremony
Oscars 2013: Winners' Press Room
Oscars 2013: Red Carpet