Steven Moffat has promised us something a little more frightening than usual this year – and he's not joking, judging by what we have seen so far

There are few things more Christmassy than a snowman. But while Channel 4 will be welcoming in Christmas with a sequel to Raymond Briggs' classic film, and John Lewis's cut a romantic, if mournful figure, the stars of BBC1's Doctor Who Christmas, come with sharp, icy teeth – and look none too friendly.

"You're very aware of the time of year [at Christmas], and the noisy, sugared-up, slightly tipsy household," said Doctor Who writer Steven Moffat. "Sometimes we play along with something a bit frothier. This year though, we might just give them a fright!"

The hour-long special, titled The Snowmen and to be broadcast at 5.15pm on Christmas Day, introduces new companion Clara and a new look for the Doctor – including a top hat. "It's a bit like the Doctor meets the Artful Dodger," said Matt Smith, who plays the time lord.

Set on Christmas Eve 1892, viewers will not only find the Doctor dealing with a tricky new villain – but also his state of mind following the loss of the Ponds. "He is slightly removed and not at his best," said Smith – but he promised that the Doctor will be getting stuck in. "Grieving has its place, but it's important to show that and then propel back into the adventure."

This Christmas the Doctor will find himself doing battle with new baddie Doctor Simeon, played by Richard E Grant, who has also appeared as the titular time lord twice – once in the animated Scream of the Shalka, and again in The Curse of Fatal Death for Comic Relief.

"When you're born with a 10ft long face, you don't get hero roles," said Grant, reflecting on playing the villain – who in this case recruits an army of evil and hungry snowmen to carry out his plans. "But I'm not complaining as I have hugely enjoyed the wide variety of parts I've got to play."

Viewers have already met Jenna-Louise Colman, who plays companion Clara, in a shock opening to the series – but she had a different name and, indeed, a rather different outfit.

"It's going to be quite a journey of discovery with Jenna and her character," promised Moffat. "For now, enough to say that the Doctor in his darkest hour, long ago in a Victorian winter, meets exactly the right person. Or does he?"