The Academy of Motion Picture Arts and Sciences has made a big push to diversify its membership in recent years, and this year's winners were more diverse than they were a few years ago when the #OscarsSoWhite campaign erupted.
As well as the triumphs for Lee, King and Ali, there were historic African-American winners behind the camera.
Ruth Carter scooped the costume design trophy, and her Black Panther crewmate Hannah Beachler shared the production design prize with Jay Hart.
It's been three decades since his landmark films She's Gotta Have It and Do The Right Thing - and now Spike Lee finally has a competitive Oscar. He already has an honorary Oscar, which he won in 2016.
He didn't win this time for best director - he won best adapted screenplay for BlackKklansman, which tells the true story of a black police officer who infiltrated the Ku Klux Klan.
In his speech, he referred to the 400th anniversary of the first slaves being taken to America.
Mahershala Ali won his second best supporting actor Oscar in three years. He won for Moonlight in 2017 and has now won for playing jazz pianist Don Shirley in Green Book.
"Trying to capture his essence pushed me to my ends, which was a reflection of the person he was and the life that he lived," Ali said.
The four awards for Bohemian Rhapsody, the authorised biopic of Queen and Freddie Mercury, included best actor for Rami Malek, who won rave reviews for playing the late singer.
"I think about what it would have been like to tell little bubba Rami that one day this might happen to him, and I think his curly-haired little mind would have been blown," he said in his acceptance speech.
The first British woman to win the prize since Kate Winslet in 2009, she added: "Any little girl who's practising their speech on the telly - you never know!"
And she endeared herself further to the audience by responding to a signal to end her speech by blowing a raspberry.
The star, who started out as a sidekick in TV sitcoms like Peep Show, was in shock when her name was called.
Glenn Close had been the firm favourite for her role in The Wife - and now has the unenviable record of seven nominations without a win.
Holding back tears on stage, Colman said: "It's genuinely quite stressful. This is hilarious. I've got an Oscar!"
British actress Olivia Colman defied the odds to scoop an Oscar on a night when Green Book also sprung a surprise by winning the award for best film.
Colman won best actress for her role in The Favourite and charmed viewers with a funny and tearful speech.
Saudi Arabia has announced that Princess Rima bint Bandar al-Saud will become its next ambassador to the US - the first woman ever to take on an envoy role for the kingdom.
Her appointment was made public in a royal decree on Saturday.
Princess Rima spent part of her childhood living in Washington DC.
She assumes the role at a difficult time, as Saudi Arabia tries to quell an international outcry over journalist Jamal Khashoggi's death.
After giving conflicting explanations of what happened, the Kingdom eventually admitted Khashoggi, who was once a Royal insider, was murdered after entering the country's consulate in Istanbul last year.
Before his death the journalist was a columnist for the Washington Post newspaper, where he frequently criticised the Saudi government.
Saudi Arabia denies that Crown Prince Mohammed Bin Salman had any involvement in his death - a claim the US intelligence community has cast doubt on.
Mrs May is expected to hold talks with European Council president Donald Tusk and other key EU figures in Egypt later during a summit between leaders of EU and Arab league countries.
But Downing Street has played down hopes of a breakthrough on her Brexit deal being reached in Sharm el- Sheikh.
The summit is the first between leaders of EU and Arab league countries and will focus on tackling concerns over security and migration, and boosting trade.
The resignations of three pro-Remain Tory MPs - Anna Soubry, Heidi Allen and Sarah Wollaston - to join a group of Labour defectors in the new Independent Group reduced the Tories working majority in Parliament to eight.
Mrs May said: "No-one gets more frustrated than I do when people vote against the whip, particularly given the tight Parliamentary arithmetic that we face.
"But we are not a party of purges and retribution. We called a referendum and let people express their views - so we should not be seeking to deselect any of our MPs because of their views on Brexit.
"Our party is rightly a broad church - on that and other issues."