Editor's note: "A Larry King Special -- Harry Potter: The Final Chapter" airs at 8 p.m. ET Friday and Saturday on CNN.
(CNN) -- When Larry King asked Daniel Radcliffe about filming his last scene as the title character in the "Harry Potter" movies, the actor described it as "very emotional. ... I kind of wept like a child on that last day."
Radcliffe also said it felt "very strange, considering we've done it for 10 years." The actor said he believes the final and eighth film, "Harry Potter and the Deathly Hallows: Part 2," is "the best out of all of them," calling it the "most exciting" and "most direct" in the series based on J.K. Rowling's books.
"I think in this film," Radcliffe said, "we find the balance best between the emotional side of the films and the action-packed adventure, exciting side."
Radcliffe will be among the guests Sunday on "A Larry King Special -- Harry Potter: The Final Chapter," which also will include interviews with Emma Watson, Rupert Grint, Robbie Coltrane, Helena Bonham Carter and others. The new movie comes out July 15. (Warner Bros. Pictures is behind the "Harry Potter" franchise. The studio, like CNN, is a Time Warner company.)
King asked Radcliffe to explain why "Harry Potter" is so successful.
"It's due to a lot of things," the actor said. "We love an underdog. I think the world of J.K. Rowling is so meticulously thought out that people like me, who like to geek out about these things, can get wrapped up in the wizarding law and the world and it's so complete, I think we love that. We love magic. We love the idea of that."
Radcliffe also said he keeps a healthy perspective by reminding himself that the fame and adulation are all about the franchise and the character.
"It doesn't matter who would have got this part," the actor admitted. "When you step out of the car at a premiere and you get hit by that wall of noise and screaming ... it's very important for me to remember that ... they would be screaming for somebody else had he got the part."
As for his post-"Potter' future, Radcliffe expressed a strong desire to have children when asked if he wanted a family.
"Oh, God yes, absolutely," said Radcliffe, who turns 22 on July 23. "I want kids and I want lots. I absolutely do. I've seen how happy fatherhood has made some of my best friends."
Radcliffe, who is starring in a revival of the musical "How to Succeed in Business Without Really Trying" on Broadway, also said the "Potter" movies instilled a work ethic in him that enables him to perform onstage eight times a week.
In a separate interview with CNN.com, King described Radcliffe as "a tremendous performer" after seeing him recently on Broadway.
"He has a long career ahead of him," King predicted. "He's got a new movie coming out next year -- a thriller, he wants to direct; he loves what he does and that's very important. The fact that he likes theater puts him in that class of actors that are regarded seriously. I think he's going to have a long and heralded career."
Radcliffe has grown up on the screen and on the set with his co-stars Watson and Grint. Watson called it an honor to have spent half her life playing the character Hermione Granger.
The actress said, "I was 9 years old, you know. I was still losing teeth, if that puts it in perspective. I was still losing baby teeth."
She added, "It's been pretty great to grow up being her. Even though I wasn't spending so much time being me."
What does Watson attribute the series' success to?
"It's just the most complete escapism," she said. "Which is what great stories are -- that you just can completely lose yourself in another world. And what I really love and what I think that people really love and why the stories are so enduring and why they touch so many people is because the characters are so, so real and flawed, and inspiring, and lovable -- completely lovable."
As for her future, the 21-year-old actress said she's "excited about having time now to pursue other roles, and so, it's bittersweet. It's real exciting to see what comes next, but it's definitely a big chapter closing."
Grint, who plays Ron Weasley in the films, reflected on the trio's uniquely magical upbringing.
He described it as "11 years of quite an intimate process ... where you're kind of with each other every day, all year, every year."
Grint said he believes audiences will be shocked at "how brutal" the latest "Harry Potter" installation is.
"It's really serious," Grint said. "Voldemort is kind of rising again. And it's really quite disturbing because we're losing characters that we've known since the first book."
The actor added, "I think it's going to be really shocking just to see the cast all just kind of collapse into this kind of burning piles of rubble."
Of the last day of filming, Grint admitted he "wasn't kind of prepared for kind of how it would feel."
"It had this real kind of weird energy about it," he said. "It was kind of like the last day of school, and I remember packing up my dressing room and putting all these kind of odd birthday cards and toys that I'd kind of collected over the years."
But Grint said the "Potter" series will "always kind of be with me. I'm really just grateful to be a part of it. I've loved every day of it."
King told CNN.com about his interview with Robbie Coltrane, who plays Hagrid in the "Harry Potter" movies.
"I had a grand time with him," King said." His sense of humor, his description of wearing the Hagrid costume, his career in theater. ... He also pointed out something I hadn't realized -- every great British actor has appeared in at least one film in the 'Harry Potter' series. Coltrane considered it a privilege to have been in the movies and was sad when it ended."
In the interview, Coltrane said his Hagrid costume weighed a whopping 100 pounds.
"There was no way around that," said Coltrane, whose character was supposed to be more than 8 feet tall. "'Cause it just -- it just had to look absolutely right."
Bonham Carter, who portrays the positively wicked Bellatrix Lestrange, admitted her character was "great fun to play" despite the fact that "she's got serious mental issues."
Bonham Carter said she was delighted to "be paid lots of money to rage around and roll." The actress also called it "a real privilege and an honor to be a part of" the "Harry Potter" films.
Aside from the interviews with the stars, Sunday's special will feature a scene from "Harry Potter and the Deathly Hallows: Part 2" that has not yet aired anywhere else.
"We're also going to take the Ralph Fiennes character of Voldemort and show you sensational footage of how he is made up," King said. "It's really extraordinary."
King, who saw a sneak preview of the new movie, said the "Harry Potter" series stacks up well against other pop culture phenomena he has seen in his lifetime, which include -- among others -- Batman, Spiderman and "The Godfather" trilogy.
"They could have made 10 'Godfathers,' " he said.