Steven Moffat thinks 'Doctor Who' is the "greatest show ever made."
The 56-year-old writer will step down as the show runner - a position he's held for seven years - in just under two weeks' time when his Doctor - Peter Capaldi - makes his final appearance as the time-travelling alien in the festive special 'Twice Upon A Time.'
But, although it's an end of an era for him, he's pleased he was part of a show that has inspired people to chase after their dreams and become anything they set their minds to.
Speaking during a Q&A after a preview screening of the Christmas special, which will air on December 25, Moffat said: "'Doctor Who' by always being different can never be perfect. Count the hearts that beat a little faster because of 'Doctor Who'.
"People change their view of the world and what they're capable of because of a silly show about a man who travels around in time and space in a police box.
"So never mind the reviews, never mind the ratings, never mind any of that. Count the scientists, the musicians, the scholars, the writers, the directors, the actors - who became what they are because of this show."
The special will no doubt draw some tears as not only is Moffat leaving, it will be the last time Peter - who has played the Time Lord for four years - steps out of the TARDIS as he'll hand the keys over to Jodie Whittaker, who will play the Doctor from next year, but the BBC's director-general Lord Tony Hall is convinced the episode will be "bittersweet".
He explained: "It was 14 years ago this week that Steven Moffat was asked to write his first episode. And he has gone on to write over 40 more. And of course, you may not know this, but he turned down Hollywood to take the reigns as showrunner in Cardiff.
"He's continued to surprise and delight us. He's a master craftsman, ingenious, adventurous and great fun and I can't wait to see what he does next.
"Quite magical and also profound."
'Twice Upon A Time' airs on Christmas Day at 5.30pm.