As soon as Matt Smith announced he would be leaving Doctor Who, speculation started on who would be the next actor to take on the iconic role.
Current favourite at the bookmakers is Ben Daniels, at 4-1.
He has previously starred in the Netflix remake of House of Cards as well as Merlin and Law and Order: UK.
Other favourites include Him and Her actor Russell Tovey, Rory Kinnear from Skyfall and Ben Whishaw who also starred in the Bond movie as Q.
Many black actors appear on the bookies' shortlists as well as a number of female names. Previously Doctor Who has always featured a white male lead.
Homeland star David Harewood, as well as Paterson Joseph, who is best known for his role as Johnson in Peep Show, are two of the black actors given good odds.
Fellow Peep Show star, Olivia Coleman, who has just won two Bafta awards, is one of the women suggested to be the first female Doctor
Jenny Colgan, who wrote the official Doctor Who novel, told the Today programme: "Anything is possible with casting.
"I love the fact that a woman is all we have to speculate about now. If they cast an actor of colour, nobody would even bat an eye, so I think the woman thing is the only thing left for people to get curious about."
Thomas Williams says, "whoever is the new doctor needs to be unknown. New to the scene and not a current personality!"
A lot of people want to see the return of David Tennant. While others think Idris Elba, Olivia Colman, Rob Sharpe or even Russell Brand would be brilliant choices.
Matt Smith's "spectacular" exit is yet to be revealed and producers say it will stay "under wraps".
They have confirmed he will return to BBC One screens in the 50th anniversary episode on Saturday 23 November.