Moffat has written more episodes of Doctor Who than any other person, but now, it's time for him to leave and let new boss Chris Chibnall fill his bigger-on-the-inside shoes.

To mark Moffat's departure, over the last year or so RadioTimes.com has asked some of the key figures in Moffat's Doctor Who tenure how they think his legacy will stand up in the years to come.

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Spoiler alert: the history books will be kind to Mr Moffat.

Peter Capaldi – Doctor Who lead, 2014-2017

“I think Steven will be remembered as probably one of Doctor Who’s greatest writers, because he has such an imaginative take on it which is also popular and emotional,” Capaldi, who makes his last appearance in Christmas Day episode Twice Upon a Time, told us.

“He’s able to create stories that are both deeply emotional and very dramatic and exciting – and he loves monsters. It’s a tricky combination, but one I think he pulls off brilliantly.”

Karen Gillan – Doctor Who companion Amy Pond, 2010-2013

“Steven will be remembered as the greatest Doctor Who writer that ever existed,” Gillan, who was one of the first people Moffat cast alongside Matt Smith for his first Doctor Who series, told RadioTimes.com. “100 per cent, he's the best.”

She added: “I shouldn't speak for him, but I think he can't wait to be a fanboy again.”

Russell T Davies – Doctor Who showrunner, 2005-2010

“Oh, good lord, there's no doubt about it – he’s been magnificent,” Davies, who handed the reins of Doctor Who over to Moffat seven years ago, said when we asked him about his successor’s legacy.

“I can't wait for that last episode; I think he's bound to let rip, don't you? I think he'll be as cheeky as all hell, and go a bit mad. He's wild and dangerous and hilarious at the best of times, and I think if there ever were any stabilisers on that bike, they're gone now! I really can't wait for it.”

Pearl Mackie – Doctor Who companion Bill Potts, 2017

“Well, I think Steven is incredible,” Mackie, who departs alongside Moffat and Capaldi this Christmas, told us. “He's such a talented man, I don't know where he comes up with all the ideas that he comes up with.

“I feel like he might have some very dark dreams! He's brilliant, and his writing is fantastic.

“Without him, Bill wouldn't have been created. He's created some of the most-watched episodes of Doctor Who ever, and some of the most terrifying monsters have been thought up in his mind.

“I think that'll be how he's remembered - a wonderful showrunner and creator of the Weeping Angels."

"He's done six seasons of Doctor Who, and that's no mean feat,” she concluded. “To keep it fresh and keep it interesting, to keep people involved and engaged – I think that's a fantastic talent, and I hope that's what people will remember at the end of his tenure.”

Michelle Gomez – Doctor Who villain Missy, 2014-2017

“With Steven Moffat, you never know what’s going to happen next,” Gomez, who played a gender-swapped version of classic Who foe the Master, told RadioTimes.com.

“Even when you’ve been in the show, like I have been for three years, there’s no time to ever get too comfortable or rest on your laurels, because there’s always going to be something. He always pulls the rug from under your feet.

“I’ll miss somebody like Steven Moffat writing me the best lines I’ve ever had in my career,” she concluded.

Mark Gatiss – series writer and actor, 2005-2017

‘Steven had a miserable time doing The Day of the Doctor, he's on record as saying that,” Gatiss, who has worked closely with Moffat in both Doctor Who and Sherlock, told us.

“But it's a f***ing triumph," he adds. "I said to him when it was all over, 'Do you know you've actually managed to please everyone? That's almost inconceivable.'"

He added that despite facing critics during his tenure, Moffat's legacy is assured.

“I did say, ‘Don't worry, because soon you will enter sainthood – because you'll stop.’ As soon as you stop, as soon as it's the past, you're fine.

"Then it will be 'Bring Back Moffat'. Of course it will. 'Death to Chibnall'. That's how it goes, isn’t it?

“I've seen how much love and care he has put, poured into Doctor Who. It is genuinely the hardest job in showbusiness, if you care. And he really loves the show, and has poured everything into it for so many years now.

“He hasn't written anything except Doctor Who and Sherlock for seven years or more. And he just wants to do something different. I think obviously he'll be judged to be one of the greats for this show.”

Doctor Who: Twice Upon a Time airs on BBC1 on Christmas Day (Monday 25^th December) at 5.30pm