British actors Peter Capaldi and Ben Daniels are gamblers' favorites to be named the next star of "Doctor Who" Sunday in a BBC special, The Observer reported.

Also rounding out the top four actors expected to take the helm of the successful BBC science fiction series are Rory Kinnear and Ben Whishaw. Until 7 p.m. London time though, only those in the inner circle of "Doctor Who" know who the actor to play the 12th Doctor really is, the British newspaper said.

"It's the biggest secret in showbiz, even those working with the new Doctor on other projects at the moment have no idea they are in the presence of the 12th incarnation," said Ben Stephenson, BBC drama controller.

Executive Producer Steven Moffat and 11th Doctor Matt Smith will be on hand during the live announcement hosted by Zoe Ball, the BBC reported.

Smith announced his intentions to leave the series in June. He will appear as the Doctor in the series' 50th anniversary special set to air Nov. 23, and his final turn as the character will be in this year's Christmas special.

The Doctor has been played by actors William Hartnell, 1963-66; Patrick Troughton, 1966-69; Jon Pertwee, 1970-74; Tom Baker, 1974-81; Peter Davison, 1982-84; Colin Baker, 1984-86; Sylvester McCoy, 1987-96; Paul McGann, 1996; Christopher Eccleston, 2005; David Tennant, 2005-10; and Smith, 2010-13.