The young stars of the ''Harry Potter'' franchise have run up against the one obstacle more formidable than Lord He Who Must Not Be Named: puberty. Rupert Grint (Ron) turns 16 later this summer, Daniel Radcliffe (Harry) turns 15 on July 23, and Emma Watson (Hermione) turned 14 last month. All of them are older than their characters, who are 13 in ''Harry Potter and the Prisoner of Azkaban,'' which opens June 4. With the fourth film (''Harry Potter and the Goblet of Fire'') shooting this summer for release in fall 2005, ''Harry Potter and the Order of the Phoenix'' barely on the drawing board, and the final two books in the series yet to be written, the franchise's producers have acknowledged that the three beloved child stars will have to be replaced. ''There will come a point when one, two, or all three of them will move on,'' producer David Heyman told the New York Post. ''I don't know when that will be -- with the fifth, sixth or seventh movies -- but it's inevitable.''
The three actors, who were greeted with Beatlemania-like screams from thousands of fans at the ''Azkaban'' premiere at New York's Radio City Music Hall over the weekend, will still appear in ''Goblet.'' Joining them are some new adult actors, Variety reports. Brendan Gleeson, currently on screen as Menelaus, Helen's wronged husband in ''Troy,'' will play the new Defense of the Dark Arts teacher, Alastor ''Mad Eye'' Moody. Also cast, as Madame Maxime, the Amazonian headmistress of Hogwarts' rival, Beauxbatons Academy, is Frances de la Tour, best known for her work on the British sitcom ''Rising Damp.'' Mike Newell (''Four Weddings and a Funeral,'' ''Mona Lisa Smile'') is directing.