Cast members (from left to right) Rupert Grint, Emma Watson and Daniel Radcliffe arrive at the world premiere of "Harry Potter and the Deathly Hallows: Part 2" held in Trafalgar Square in London on Thursday, July 7, 2011. This is the final film in the Harry Potter series which is based on the best-selling novel by J. K. Rowling. It will be released in British cinemas on July 15. [Photo: CFP]

The world premiere of "Harry Potter and the Deathly Hallows: Part 2" was held in London on July 7.

The stars of the Harry Potter films worked the red carpet for the last time together on Thursday before the world premiere of the saga's final installment in London.

Thousands of Potter fanatics screamed as the stars of the epic movie series gathered for the launch of "Harry Potter and the Deathly Hallows: Part 2", the action-packed finale to one of the most successful movie franchises of all time.

The film sees boy wizard Potter take on the evil Lord Voldemort in a climactic showdown, the second of two movies based on the seventh and final Potter book by British author J. K. Rowling.

Fans from around the world have slept out in London's Trafalgar Square, some for more than six days, desperate to catch a last glimpse of the film's stars all together. Organisers said 8,000 people had gathered at the event.

Some wore sorcerers' capes, while others waved magic wands or were dressed as their favourite characters.

Despite the excitement, some fans could not hide their sadness at bidding farewell to the Potter magic.

Tiffany Milow, 22, a London-based student from Dallas, Texas, said: "I've been reading the books since elementary school. I'm torn apart that this is the last one, I'm devastated."

Rowidah Alnajar, a 20-year-old Saudi woman who lives in London, said she had spent the night in a sleeping bag to be in position.

"It's really important for me. It's the end of my childhood. I can't believe it," she told AFP.

Lou Ravelli, 13, waving a fake wand and wearing a sorcerer's cloak, said: "It's the greatest day of my life. I'm a lifelong fan. I'll be so happy if I get to meet them!"

Rupert Grint, who plays Potter's sidekick Ron Weasley, said it was an emotional time for the actors too.

"These last few months I've been in a bit of denial, I think, accepting the fact that it really is over," he told BBC television.

"When I saw the posters in capital letters, 'It all ends', it really does imprint that on the mind. I will miss this. It's been amazing."

Emma Watson, who plays Hermione Granger, spent hours signing autographs on the red carpet, and described making the films as "the best part of my life".

Director David Yates told reporters: "With Harry Potter, they (the fans) like the characters, coming back to see them, it's a fantastic world that's really involving and you want to see how it all comes out."

That chimed with Kay Miller, 42, from Stirling in central Scotland.

Dressed in a Griffindor scarf and hat and sporting a temporary Slitherin tattoo, she said: "There's a fantastic atmosphere down here. I've met people from all around the world.

"I really want complete satisfaction from the film. I want to have the whole saga wrapped up so that we're not left hanging!"

Daniel Radcliffe, who plays Potter, is taking time off from appearing in a Broadway musical to attend the premiere alongside Watson and Grint.

Fans gather at the global premiere of Harry Potter and The Deathly Hallows: Part 2, the last film of the series, at Trafalgar Square in London, Britain, July 7, 2011. (Xinhua/Yang Xiaohan)

Cast members, comprising some of the best-known names in British cinema including Ralph Fiennes, Helena Bonham Carter, Gary Oldman and Robbie Coltrane were also expected to attend.

The stars walked from Trafalgar Square to Leicester Square -- the traditional home of movie premieres in Britain -- through streets transformed into Diagon Alley, the London hub of the fictional wizarding world, with shops selling cauldrons, pumpkins and wands.

They began greeting the fans three hours before the 7:00 pm (1800 GMT) simultaneous screenings in three Leicester Square cinemas.

The film will hit British and US cinemas on July 15 and is the first Potter movie in a 3D version as well as the regular 2D release.

The first Harry Potter film was released in 2001 and the seven movies so far have earned 6.4 billion dollars (4.4 billion euros) globally.

"Part 2" covers the final third of the last book and is a fast-paced adventure, in contrast to "Part 1" which served as a scene-setter.

More than 400 million copies of the Potter books have been sold since struggling single mother Rowling published the first instalment, "Harry Potter and the Philosopher's Stone", in 1997.

The young sorcerer's exploits soon became a global phenomenon with the books now available in 69 languages and the films mesmerising audiences worldwide.

Despite the films and books coming to an end, Rowling last month unveiled an interactive website featuring new material about Potter's world.