(SOUNDBITE OF THEME MUSIC, "DR. WHO")
RACHEL MARTIN, HOST:
That music should instantly transport you to the realm of British sci-fi and the world of "Dr. Who." If it doesn't, then bear with us and listen closely. The cult BBC TV show, about a doctor who travels though time and space in a blue policeman's telephone booth, is 50 years old this year. Still with me?
The Doctor has been played by 11 different actors in those five decades. But it's not like the audience is supposed to pretend they don't notice the change. Because each time a new Doctor takes on the role, his character regenerates into a different body. So in 1963, he was played by William Hartnell.
(SOUNDBITE OF TV SERIES, "DR. WHO," 1963)
WILLIAM HARTNELL: (as Dr. Who) It's still a police box. Why hasn't it changed? Dear, dear, how very disturbing.
MARTIN: Who then regenerated in Patrick Troughton in 1966.
(SOUNDBITE OF TV SERIES, "DR. WHO," 1966)
PATRICK TROUGHTON: (as Dr. Who) I - I, I'm a scientist, I've come to talk with you.
MARTIN: Who regenerated into Jon Pertwee in 1970.
(SOUNDBITE OF TV SERIES, "DR. WHO," 1970)
JON PERTWEE: (as Dr. Who) Lead - what does lead mean to you Jo?
KATY MANNING: (as Jo Grant) Radiation?
MARTIN: I wonder how that episode ended. Anyway, skip ahead another eight incarnations, and later today, fans and Whovians around the globe will find out who will play the Doctor Number 12. The incumbent is actor Matt Smith who's played the part since 2009. Among those hotly tipped to replace him are Idris Elba of the "Wire" and "Luther" fame, and Rory Kinnear from the latest "James Bond" films.
So hold on to your hats, because at 2 P.M. Eastern Time today, all will be revealed in front of a live audience on the BBC.
(SOUNDBITE OF THEME MUSIC, "DR. WHO") Transcript provided by NPR, Copyright NPR.