Birdman, a dark satire of show business and fame directed by Alejandro Inarritu, has won this year's Academy Award for Best Picture, the film industry's highest honour.
The film portrays a washed-up former superhero actor, played by Michael Keaton, and his struggle to make a comeback in a Broadway play.
Inarritu also won for Best Director, and Birdman also won Best Cinematography and Best Original Screenplay.
Eddie Redmayne won for Best Actor for his break-out role as physicist Stephen Hawking in the biographical movie The Theory of Everything.
Julianne Moore won the Best Actress Oscar for her role as a university professor with Alzheimer's disease in Still Alice.
She used her speech to raise awareness for Alzheimer's disease - in Still Alice, she plays a 50-year-old who has early onset Alzheimer's.
"I'm so happy, I'm thrilled that we were able to shine a light on Alzheimer's disease," she said.
"So many people who have this disease feel marginalised. People who have Alzheimer's disease deserve to be seen so we can find a cure."
Redmayne was honoured for his portrayal of physicist Stephen Hawking, who has motor neurone disease (ALS).
Accepting his award, he thanked the Hawking family, including Jane Hawking on whose book the film is based, and said his award belonged "to all of the people around the world battling ALS".
Richard Linklater's Boyhood won just one award from six nominations - Best Supporting Actress - which went to Patricia Arquette.
Arquette thanked "her Boyhood family" and "every woman who gave birth".
"To every woman... we have fought for everybody else's equal rights. It's our time to have wage equality," she added, to huge applause from the audience.
JK Simmons won Best Supporting Actor for Whiplash, in which he played a strict drumming teacher at a music conservatory.
Whiplash also won the award for Best Editing and Best Sound Mixing.
The Grand Budapest Hotel picked up Best Costume Design, as well as Best Hair and Make-Up, Best Score and Best Production Design.
Hannon thanked absent actor Bill Murray - who has a cameo in the film - for introducing her to director Wes Anderson on the set of his film Rushmore 17 years earlier.
Best Foreign Language Film went to Polish black and white family drama Ida.
John Legend and Common's track 'Glory', from civil rights drama Selma, won Best Song.
Legend used his time on stage to deliver a political message, saying: "We live in the most incarcerated country in the world... people are marching with our song... we are with you, march on."
The 87th Academy Awards took place at Hollywood's 3300-seat Dolby Theatre.
Performers at this year's ceremony included Lady Gaga - who sang a medley of Sound of Music songs to celebrate the classic film's 50th year - Jennifer Hudson and Anna Kendrick.
The full list of winners at the 87th Academy Awards