A Christmas Carol reunites Matt Smith, Karen Gillan and Arthur Darvill and guest stars Michael Gambon (Harry Potter, The Singing Detective) and Katherine Jenkins. Right now we don't know much about the special, but earlier in the year, Lead Writer and Executive Producer, Steven Moffat, confirmed, 'Oh, we're going for broke with this one. It's all your favourite Christmas movies at once, in an hour, with monsters. And the Doctor. And a honeymoon. And ... oh, you'll see. I've honestly never been so excited about writing anything!'