'Doctor Who' Star Sends Comforting Letter to Child Worried About Regeneration

Peter Capaldi said goodbye to all Doctor Who fans on Christmas Day. Only one Doctor Who fan received a handwritten letter from the Doctor.

On Twitter, a fan named Brian McGilloway shared his son's story. The 9-year-old was feeling anxious about the Doctor's regeneration.

"Peter Capaldi is my 9-year-old son's fav Doctor Who and he was dreading his regeneration," McGilloway tweeted. "And then he got this letter with some words of comfort from the Doctor himself among his Santa presents. Such a kind man."

McGilloway shared a photo of the letter, which reads:

I hope you are having a very merry Xmas. Xmas is always good fun. Well not always. Not every single second. Regenerating is not completely good fun. And it usually happens about Xmas-time. But you know what? Even though it can be a little bit icky (like really bad flu) it has always, always turned out good for Dr. Who. The new Doctor always becomes your favorite and the one that goes...well, he never really goes, he is always there, somewhere in time and space, and if you think about him hard enough you'll see him, and he'll see you.

It's like the Doctor says, "Everything ends and its always sad. But everything begins again, and that's always happy. Be happy."

So, have a brilliant Xmas, a happy new year and a wonderful life - I'm sure you will."

Capaldi signs the letter both as himself and as the Doctor.

Capaldi's Twelfth Doctor regenerated into Jodie Whitaker's Thirteenth Doctor during the Christmas Special. The regeneration brought out some strong reactions from fans.

Doctor Who will return in 2018.