Leonardo DiCaprio ended years of disappointment while Spotlight was the surprise winner of best picture on an Oscars night dominated by the diversity controversy.
Hollywood heartthrob DiCaprio beat Eddie Redmayne, Bryan Cranston, Matt Damon and Michael Fassbender to take home the best actor gong for his role in The Revenant at the 88th Academy Awards.
The star was first nominated for an Oscar 23 years ago in a supporting role, and has since been nominated four more times for acting, including this year, but had never won until now.
Newspaper drama Spotlight was the underdog in the best picture category but was triumphant in beating favourite The Revenant to the coveted award.
Thought of as the top honour handed out by the Academy, Spotlight was not widely expected to win best picture and the film won only one other award on the night, taking the gong for best original screenplay.
Such a sparsely-awarded best picture winner has not appeared since 1952's The Greatest Show On Earth.
Spotlight is about the Boston Globe's investigative reporting on sexual abuse by Roman Catholic priests.
The film, which was nominated for six Oscars, looks at the scandal in Boston, and the collusion and reluctance of the local community to face up to it.
Host Chris Rock did not shy away from the diversity issues plaguing this year's awards and opened the ceremony by declaring Hollywood is "racist" and admitting he considered boycotting the ceremony because of the absence of black nominees.
The comedian, who welcomed the audience in the Dolby Theatre to the "white People's Choice Awards", cracked a series of jokes about the race issue and added the controversy over police shootings of black suspects in the US to his targets.
He said: "Everyone wants to know is Hollywood racist? You have to go at it the right way. Is it burning-cross racist? Fetch-me-some-lemonade racist? No. It's a different kind of racist.
"Is Hollywood racist? You're damn right it's racist but it's sorority racist."
He added: "That's how Hollywood is but things are changing."
Rock ended the ceremony saying the night had been an "amazing experience" but threw in one last diversity dig as he quipped "black lives matter".
Academy president Cheryl Boone Isaacs took to the stage to address the diversity issue and quoted Dr Martin Luther King.
She stressed that all members of the academy and "everyone in this room help deliver that message, each of you is an ambassador who can help influence others in the industry. It's not enough to just listen and agree, we must take action. While change is often difficult, it is necessary."
Accepting his award, which he was widely tipped to win, DiCaprio used his last few minutes on stage to campaign for climate change, adding: "It is happening right now. It is the most urgent threat facing our species, and we need to work collectively together and stop procrastinating."
Room star Brie Larson was named best actress in a leading role, and The Revenant's Alejandro G Inarritu was named best director for the second year in a row.
The most awards of the night went to Mad Max: Fury Road, which managed to take home six Oscars in total, followed by The Revenant with three and Spotlight winning two.
A British star who scooped a surprise victory was Mark Rylance, who was named best supporting actor for his role in Bridge Of Spies, beating Sylvester Stallone, Mark Ruffalo and fellow Britons Christian Bale and Tom Hardy.
Alicia Vikander picked up the best supporting actress Oscar for her role in The Danish Girl.
Other notable British successes included Amy, the British-made film about the late Amy Winehouse, which won the Oscar for best documentary feature film, and Jenny Beavan, who won best costume design Oscar for Mad Max: Fury Road.
Beavan, who wore a jacket from Marks & Spencer to the Oscars, was famously described as a "bag lady" by Stephen Fry at the Baftas.
British singer Sam Smith picked up the best original song Oscar and dedicated his award to the lesbian, gay, bisexual, and transgender (LGBT) community.
Smith co-wrote the song Writing's On The Wall with fellow Briton Jimmy Napes for the latest James Bond movie, Spectre. He follows in the footsteps of Adele, who won the Oscar in 2013 for the Bond instalment Skyfall.
An emotional Smith took to the stage with Napes and said: "I read an article a few months ago by Sir Ian McKellen and he said no openly gay man had ever won an Oscar. I want to dedicate this to the LGBT community all around the world. I stand here tonight as a proud gay man and I hope we can all stand together as equals one day."
Celebrating his win backstage, Smith said he wished he could discuss his triumph with Sir Ian.
He told the Press Association: "I wish I had his number, I don't know him, I just love Gandalf."
In the winners' room, DiCaprio said: "I also got to talk about something I have been obsessed with - the environment and climate change - on a platform with hundreds of millions of people watching worldwide. This is the biggest crisis our world has ever known, I've been making a documentary about this and the time is now, it is imperative that we act."