Photo by: Jim Spellman / WireImage
Puberty Pushing Harry Potter Stars Out | Daniel Radcliffe
Harry Potter may be a great wizard, but not even he can stop puberty.

So it goes for Harry Potter star Daniel Radcliffe and his costars, who may have to be replaced for the fifth installment of the massively popular J.K. Rowling book series, producers say.

The third movie, Harry Potter and the Prisoner of Azkaban, hits screens on June 4.

Radcliffe turns 15 on July 23, and is already two years older then the character he plays. Costars Rupert Grint (who plays Ron Weasley) and Emma Watson (Hermione Granger), also both 14, continue to grow as if there's no tomorrow – which there might not be.

"There comes a point when one, two or all three of them will move on," Harry producer David Heyman said at a New York press conference, according to Reuters. "I don't know when that will be – with the fifth, sixth or seventh movies – but it's inevitable."

Radcliffe and the other kids, who have already done three movies (Harry Potter and the Sorcerer's Stone, Harry Potter and the Chamber of Secrets and the new Prisoner of Azkaban) are now shooting the fourth film, Harry Potter and the Goblet of Fire, which started three weeks ago.

So far, none is signed for movie No. 5, Harry Potter and the Order of the Phoenix.

Says Radcliffe of his and his costars' eventual planned obsolescence: "It would be very hard to watch someone else playing the parts, but I'm just taking it one film at a time."
This week's cover

On Newsstands Now!

JOSH & FERGIE: ROCKED BY SCANDAL

Did he cheat with a stripper?

Married less than a year, the couple denies an Atlanta woman’s claims that she and Josh had a fling
Note that this week’s cover of PEOPLE may differ regionally

Save $1.00 off this week's issue. Click here for coupon