John Lithgow shares biggest worry about playing Albus Dumbledore in Harry Potter TV reboot

John Lithgow, who is taking the role of Albus Dumbledore in the new 'Harry Potter' series, opened up about his one fear while signing up for the role.

In the new documentary, 'Finding Harry: The Craft Behind the Magic,' for the forthcoming TV reboot of the famous film franchise, the 80-year-old actor dished on the cons of filming the role at his age.

“I knew that while I did the first season of Harry Potter, I would be turning 80 years old,” he shared, explaining, “That meant that I would age to about 88 before it was all over."

John admitted, "This is an extremely difficult thing to contemplate.”

While mentioning the young cast of the HBO series, including Arabella Dominic McLaughlin, Stanton and Alastair Stout, who are taking on the roles of Harry, Hermione and Ron, respectively, John said, “They're gonna grow up in this. And I'm gonna grow older with them.”

The 'Daddy's Home' 2 actor further praised the new cast, calling Dominic, McLaughlin, Stanton and Alastair “an amazing ensemble” who “all adore each other.”

The Harry Potter TV series is all set to release on December 25 on HBO Max.