NEW YORK — When the "Harry Potter" film series is completed, its three young stars — Daniel Radcliffe, Emma Watson and Rupert Grint — will have inhabited their roles longer than Sean Connery played James Bond, Christopher Reeve was Superman or Jerry Seinfeld played himself on "Seinfeld."

Radcliffe, Watson and Grint have already effectively spent half of their lives in J.K. Rowling's universe. Radcliffe, who is now 19, was 11 when he was cast as the boy wizard for the series' 2001 debut. Watson, now 19, was 10 when she auditioned for the whip-smart Hermione Granger. Grint, the eldest of the trio, is 20.

"I've probably been Ron as long as I've been Rupert," says Grint, who plays Ron Weasley, the ginger-haired, perpetually hungry friend of Harry and Hermione.

The cast and crew have taken a break from filming Rowling's last "Potter" book — to be spread out in two films — to publicize the series' sixth installment, "Harry Potter and the Half-Blood Prince" — which arrives in theaters Wednesday.

Early reviews of the film — the second one directed by David Yates — have been positive; both Variety and The Associated Press suggested it was the best "Potter" film yet. The movies have gotten progressively more complex, darker and realistic — even amid the fantasy world of Hogwarts School of Witchcraft and Wizardry.

As the films have matured, so has the cast.

More so than any other installment, "The Half-Blood Prince," shows that Radcliffe, Watson and Grint have gone from children to young adults. To watch the first "Potter" film is to be reminded how young the actors were when they began.

With the end of the films looming, its young stars appear to have emerged from the most treacherous of adventures — child actor stardom — as remarkably grounded people and increasingly talented actors.

"For me to look back on the old films is an almost entirely destructive thing to do," says Radcliffe. "I just torture myself over it. I mean, I was young. I can't be held accountable for the performance I gave in the first two films: I was 11 and 12. I wasn't like Dakota Fanning ... who could seemingly just do it. It was very much a child's performance."

Such awareness is common for Radcliffe, who goes by "Dan." Shy as a child, Radcliffe has grown into a quick-witted, animated 19-year-old who relishes frantic chatter about indie music, the behind-the-scenes aspects of filmmaking and his burgeoning love of acting. Michael Gambon, the esteemed veteran actor who plays Hogwarts headmaster Dumbledore, says: "He's not a boy anymore. ... You can see it in his face."