Among the 60,000 spectators at Olympic Stadium will be Queen Elizabeth II — who as British head of state will officially open the games — along with royals including Prince William and his wife Kate, and Prince Harry.
There's sure to be a sprinkling of showbiz royalty, too, with Brad Pitt and Angelina Jolie, recently filming in Britain, the most often-cited names — though the first celeb spotted arriving was British actor Richard E. Grant.
British movie star Orlando Bloom stopped to take pictures with British soldiers and fans outside the stadium.
"I'm a big fan of Danny Boyle, so I'm excited to see what he's done!" Bloom said.
Actor Hugh Bonneville, who plays aristocrat Lord Grantham in the costume drama "Downton Abbey," tweeted a picture of his fellow cast-members arriving at the stadium.
The British government says more than 80 heads of state and government will be in the audience, including royalty from Brunei, Luxembourg, the Netherlands, Spain and Sweden.
The U.S. will be represented by first lady Michelle Obama, and Republican presidential hopeful Mitt Romney will also attend.
Beckham, who helped bring the games to London and said he has a role in the ceremony, will be there.
"Today is going to be an amazing moment," Beckham said Friday.
British newspapers also have speculated that boxing great Muhammad Ali may be involved.
The show, a 27 million pound ($42 million) spectacular titled "Isles of Wonder," will end with a performance by Paul McCartney.
Associated Press Writer Cassandra Vinograd contributed to this report.