What will it take to be the 12th Doctor?

Guest contributor Mark White examines.

It’s the end of another era for Doctor Who, as Matt Smith announced on Saturday that he is to leave the show this Christmas. He will not return for 2014’s Series 8, as fans had previously expected him to, and he now has only two stories – the anniversary special and the 2013 Christmas special – left in his tenure. In four short years, Smith has brought a continuum of excitement, exuberance, sinister darkness and interesting headwear to the role, and he’ll be sorely missed by fans.

Doctor Who wouldn’t be the fifty-year-old institution of a show that it is though without its aspect of change. Smith is merely the eleventh man to fly to the TARDIS, and though mourning has begun in the Whoniverse, speculation has already gripped fans of who the Twelfth Doctor will be.

Matt Smith somewhat broke with tradition when he was cast at the age of 26 to portray a 900-year-old man. Though many doubted that he could handle the role, he’s impressed both fans and critics and achieved what many believed was an impossible task, of following in the footsteps of David Tennant. Thanks to Smith’s eccentric portrayal, the role has never been more open to actors; the days of BBC English have gone for the Doctor, thanks to David Tennant’s faux-cockney twang and Christopher Eccleston’s Mancunian take on the Time Lord (“lots of planets have a north!”), and Moffat has even hinted that the Doctor may regenerate into a woman one day.

Both Idris Elba and Chiwetel Ejiofor being linked with the role – and for the role of Bond in Elba’s case – certainly indicates that the Doctor isn’t limited to being white, and the surprisingly high odds for David Tennant to return really does suggest that fans believe anything can happen.

If there’s one quality that Moffat and co. will be looking for in a potential new lead though, it’s a mercurial streak. The Doctor is an exciting, impulsive, genuinely hilarious and painfully lonely character that’s been unrivalled by any other television personality, past or present, and it though it takes a great actor to portray him, it takes someone with a special charisma. Jon Pertwee may have been in his fifties when he took the role, but he invigorated the character with energetic enthusiasm and an action-man quality; likewise, Tom Baker felt like a true alien, and David Tennant connected so powerfully with his audience because he brought a sense of fun to the character that Christopher Eccleston didn’t, for all the doom and gloom of the Time War.

Whilst surprise bookies’ frontrunner, 35-year-old Rory Kinnear (Skyfall), has both the presence and demeanour to take on the role of a thousand-year-old Gallifreyan, it’s no wonder that Benedict Cumberbatch is a name being touted by fans. Cumberbatch, who’s already worked with Moffat and expressed interest at a long-term role in Who, has earned enthusiasts a-plenty for his masterfully capricious take on Sherlock Holmes; though it may prove more than Doctor Who – something that he can’t exactly film much around – to prize him away from his ever-accumulating admirers in Hollywood, he’s certainly the figure of a Doctor that fans want to see.

Cheaper, easier options may prove to be Ben Whishaw (also of Skyfall), Rafe Spall (Prometheus, Life of Pi), Robert Sheehan (Misfits) or even a certain Hugh Laurie, who’s back in the UK after completing the last series of House.

It might seem unlikely that the BBC will cast anyone other than the archetypal white, middle class British 35-year-old male to play the Doctor, because the world are watching; not only because of the anniversary, but also due to the rising profile of the show overseas. But surely if there’s one thing that Matt Smith has taught us, it’s that anyone can be the Doctor: it doesn’t matter if the lead actor is 26, or if he’s Scottish, shaven-headed, short, hat-wearing or only available for a year. The character of the Doctor boils down to two rather contradictory traits: the years of pain and loss that gives the show its drama and heartbreak, and the otherworldly silliness that appeals to children. It doesn’t matter who it is: as long as he feels like the Doctor, he’s right.