Leonardo DiCaprio won his long-awaited first Oscar for revenge epic "The Revenant" but journalism drama "Spotlight" took best picture in a surprising end to Hollywood's glittering awards season.
The night was overshadowed by a simmering race row, addressed head-on by black host Chris Rock, who delivered a series of caustic jokes targeting the Academy's overwhelmingly white male membership.
As well as DiCaprio's best actor award, "The Revenant" on Sunday picked up the statuettes for best director for Alejandro Gonzalez Inarritu -- his second in a row -- as well as for best cinematography.
The film had only taken one other award -- best original screenplay -- and Hollywood's Dolby Theatre gasped as a stunned cast and crew headed onstage to accept the trophy.
READ more: Oscars 2016: Winners list in full
"This film gave a voice to survivors. And this Oscar amplifies that voice, which we hope will become a choir that will resonate all the way to the Vatican," co-producer Michael Sugar told the audience.
"Pope Francis, it's time to protect the children and restore the faith."
A defeat for "Creed" star and Tinseltown darling Sylvester Stallone was the other big surprise of the night, as he was snubbed for best supporting actor, with the trophy going against the odds to Britain's Mark Rylance for "Bridge of Spies."
George Miller's stark action epic "Mad Max: Fury Road" was the big winner in the technical categories, taking home Oscars for best costumes, production design, make-up, film editing, sound editing and sound mixing.
DiCaprio's success for his grueling star turn as 19th century fur trapper Hugh Glass came 22 years after his first of four unsuccessful acting nominations. For the 41-year-old actor, the fifth time was a charm.
He thanked a long list of figures who have helped him in his career, including filmmaker Martin Scorsese, before speaking on his passion -- climate change.
"Climate change is real. It is happening right now. It is the most urgent threat facing our entire species and we need to work together and stop procrastinating," DiCaprio said to applause.
First-time nominee Brie Larson picked up a widely predicted best actress statuette, having dominated the awards season with her performance as a kidnapped mother in "Room."
But it was not all celebration, as a row over the lack of ethnic minority acting hopefuls overshadowed Hollywood's biggest night.
"Well, I'm here at the Academy Awards -- otherwise known as the white People's Choice awards. You realize if they nominated hosts, I wouldn't even get this job," joked Rock, 51, who continued with a series of jibes at the Academy throughout the night.
For the second year running, all 20 nominees in the main acting categories were white, and an angry social media backlash under the hashtag #OscarsSoWhite has grabbed the awards season headlines.
Rock, who hosted despite calls for him to join a boycott, unleashed a fierce monologue -- one he apparently rewrote in the wake of the scandal to hold the Academy's 6,000-plus voting members, overwhelmingly white men, to account.
Former radio DJ Inarritu, just the third filmmaker to win back-to-back Academy Awards for best director, picked up the theme as he hailed his latest Oscar as a tribute to diversity.
"There is a line in the film that says, 'They don't listen to you when they see the color of your skin'," Inarritu said.
"So what a great opportunity to our generation to really liberate ourselves from all prejudice and, you know, this way of thinking and make sure for once and forever that the color of skin becomes as irrelevant as the length of our hair."
The first acting award of the night went to Sweden's Alicia Vikander, who dazzled on the red carpet in a strapless pale yellow Louis Vuitton gown, for her supporting role in transgender love story "The Danish Girl."
"This is insane," a visibly moved Vikander said, hailing her co-star Eddie Redmayne: "Thank you for being the best acting partner. I could have never done it without you. You raised my game."
It was a huge night for "Spotlight" director Tom McCarthy, who also picked up the Oscar for best original screenplay.
Adam McKay and Charles Randolph took the adapted screenplay Oscar for financial crisis satire "The Big Short" -- which had also been a best picture contender.
Mexico's Emmanuel Lubezki made history with his third consecutive Oscar for cinematography, for his dramatic work on "The Revenant."
One of the moments of the night came when Lady Gaga led the Oscars in a rally against campus sexual assault, bringing together survivors who joined arms in solidarity.
The pop star, who recently has spoken out about being raped as a teenager, was introduced by Vice President Joe Biden, who personally took part in Hollywood's biggest night to lend his voice to the cause.
Erik Davis, managing editor of film website Fandango described the evening as "one of the most consistently entertaining Oscar shows in memory."
"Whether or not it was intentional, the show had a unifying theme, and every Chris Rock joke was a perfect riff on that theme," he said.