Speculation abounds as to who will replace Matt Smith on 'Doctor Who'

Doctor Who is the stalwart series for BBC, having lasted for fifty years minus a few hiatuses. With the recent lead actor's declaration of leaving the show, the internet is chaotic with possible replacements.

In a long running work around for the Doctor Who series, the lead character (an alien) is able to regenerate upon death and become a new incarnation of himself with all the memories but with a new look and personality. The show uses this to replace the lead actor so that the program lasts longer than any of its participants.

Earlier this week, theCelebrityCafe.com reported on BBC's announcement that Matt Smith, the eleventh and current Doctor, would be leaving the series after the 2013 Christmas Special.

This means a new Doctor, which excited speculation across the internet. In fact, The Hollywood Reporter reports that a British bookie, William Hill, is running odds on the potential replacements.

NME reports that a source at BBC says that the revelation should come next month. In the meantime, we're left guessing.

The only fast rule when casting the Doctor is to pull from the United Kingdom. Fandom would be utterly shocked if an American was placed in the role.

The Mirror reports that the number one suspect is Rory Kinnear, who had a role in the latest James Bond movies. As a lesser known actor with familial ties to classic BBC programs, Kinnear represents the usual route.

Other front runners include Harry Potter alums Rupert Grint and, get this, Emma Watson. That's right, the Doctor's gender is not a rule. In fact, sites like Slate are calling for the next Doctor to be female.

Another fan favorite for the role is Benedict Cumberbatch, of Sherlock, Star Trek: Into the Darkness, and The Hobbit, according to The Hollywood Reporter. But his already established career could limit his availability.

A midst the speculation, one thing is certain; the next month is going to be a long one for Whovians.