Leonardo DiCaprio has finally won his first Oscar for survival epic The Revenant, after six nominations.
He was named best actor at the 88th Academy Awards, with Brie Larson named best actress for Room.
Spotlight took home the best picture Oscar with Mad Max: Fury Road picking up the most awards of the night, with six accolades.
Mark Rylance won the best supporting actor Oscar, with fellow Briton Sam Smith winning best original song.
Among the winners for Mad Max: Fury Road - nominated for 10 Oscars including best director for George Miller - was British designer Jenny Beavan, for best costume design.
The Revenant won three of the 12 awards for which it was nominated. Alejandro Inarritu also won best director and Emmanuel Lubezki won his third Oscar for cinematography in a row, having won in 2015 for Birdman and 2014 for Gravity.
DiCaprio received a standing ovation as he picked up his award, after five acting nominations and one nomination as producer of best picture nominee Wolf of Wall Street.
He thanked his director and co-star Tom Hardy for his "fierce talent on screen" and "friendship off screen" before campaigning for action to combat climate change, saying making The Revenant was "about man's relationship to the natural world".
"Climate change is real - it is happening right now," said DiCaprio. "It is the most urgent threat facing our species, and we need to work collectively together and stop procrastinating."
He asked the audience to "support leaders around the world who do not speak for the big polluters or the big corporations but who speak for all of humanity, for the indigenous people of the world, for the billions and billions of underprivileged people who'll be affected by this".
He added: "Let us not take this planet for granted. I do not take tonight for granted."
It is 22 years since he was first nominated for an Academy Award, having been nominated for best supporting actor for What's Eating Gilbert Grape.
Speaking to reporters after his win, DiCaprio said: "I feel very honoured, to share this has been an amazing experience, to sit there and talk about the film.
"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."