Dame Helen Mirren has been named best actress at the Venice Film Festival for her role as Queen Elizabeth II.
Dame Helen has won high praise for her performance in The Queen, about the aftermath of Princess Diana's death.
Ben Affleck was named best actor for his role in Hollywoodland. He portrays late US actor George Reeves, who played Superman on TV in the 1950s.
Chinese film Still Life, about the effects of the Three Gorges Dam, took the Golden Lion prize for best film.
In all, 22 films competed for the awards, with last year's Golden Lion going to cowboy drama Brokeback Mountain.
Dame Helen's award comes just two weeks after she won an Emmy - the US TV equivalent of an Oscar - for playing Elizabeth I.
The 61-year-old actress was introduced on the Venice ceremony stage as "Her Majesty Helen Mirren".
Accepting her award, she said: "It's always terrifying seeing your movie take its first steps, but its an incredible honour for our film to take them at the Venice festival."
She added that she was "just a bit of the DNA of the film", saying the movie's mother was screenwriter Peter Morgan and its father was director Stephen Frears.
The Queen, which was the only British film in competition, also picked up best screenplay.
Collecting his prize, Mr Morgan joked: "Thank you Tony Blair for timing your political disintegration with the release of our film."
As well as Dame Helen - who has been tipped for an Oscar nomination - The Queen features James Cromwell as Prince Philip and Michael Sheen as UK Prime Minister Tony Blair.
The film portrays the royal family's struggle to come to terms with the public reaction to the princess's death in 1997, including demands for a show of mourning from the monarchy.
Chinese director Jia Zhang-Ke was a surprise recipient of the Golden Lion
Before Saturday's ceremony, The Queen was thought to be among the favourites for the Golden Lion.
Still Life, directed by 36-year-old Jia Zhang-Ke, was a late entry to the festival's line-up.
It tells the story of a miner and a nurse who return to a town that is being submerged by the dam's construction.
Actress Catherine Deneuve, who headed the jury, described it as "a very special film".
She praised "the beauty of the cinematography and the quality of the story, without getting political", and said: "We were very touched and we were very moved."
But critics were less impressed. Hollywood bible Variety said Still Life was "slow", "aptly titled" and had "almost zero plot".
Ben Affleck stars in Hollywoodland with Bob Hoskins and Diane Lane
And Screen Daily described it as a "slow, elaborate, thoughtful" film that "will not gain much of an audience beyond festivals or very specialised programming".
The best director award went to Frenchman Alain Resnais for Private Fears in Public Places, while the special jury prize went to Daratt, Chad's first entry in the competition.
Hollywood film Bobby, centred on the assassination of Senator Robert Kennedy, was another film to be earmarked as a favourite before the ceremony.
But its director Emilio Estevez and cast including Sharon Stone, Sir Anthony Hopkins, Demi Moore and Lindsay Lohan won nothing.
The Venice event is considered second only to Cannes in terms of prestige on the film festival circuit.
The success of The Queen comes two years after Mike Leigh's acclaimed Vera Drake won the Golden Lion and actress Imelda Staunton picked up best actress.