Rupert Grint and Emma Watson talk with each other during a photocall outside St. Pancras Hotel in London on July 6, 2011. Grint plays Ron Weasley and Watson plays Hermione Granger in the films. The final Harry Potter film has its world premiere in London tomorrow, an action-packed finale bringing the curtain down on a saga that has enthralled audiences worldwide.  'Harry Potter and the Deathly Hallows -- Part 2' will see the boy wizard take on the evil Lord Voldemort in an epic showdown. Hundreds of Harry Potter fans have been camping out for days in London's Trafalgar Square to secure a prime spot at the world premiere.  AFP PHOTO ADRIAN DENNIS (Photo credit should read ADRIAN DENNIS/AFP/Getty Images)