Doctor Who fans are preparing for the 40th anniversary of the sci-fi show's television debut on Sunday.
Tom Baker was one of the most popular Doctors
The show first appeared on the BBC in 1963, with William Hartnell taking the lead role as the time-travelling hero.
It grew into a much-loved institution, before being axed in 1989, by which time Sylvester McCoy was the seventh actor to play the Doctor.
Now fans are speculating as to who will take the lead role in a revival of Dr Who, due to be broadcast in 2005.
The new series is in the early stages of development, and is being written by TV dramatist Russell T Davies.
Buffy the Vampire Slayer star Anthony Head was voted favourite in a recent poll for Radio Times magazine.
Whoever gets the role will also follow in the footsteps of Patrick Troughton, Jon Pertwee, Tom Baker, Peter Davison, and Colin Baker.
Hopes were raised of a comeback in 1996 when Paul McGann recreated the role in a TV movie version, co-produced by the BBC and the US Fox network.
The first Doctor: William Hartnell
But while it was a success in the UK, it failed to get the backing in the US for a new series to be made.
Since then, McGann, Colin Baker and Richard E Grant have provided the voice of the Doctor for animated adventures on the BBC website, and radio versions of the series have also been made.
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Doctor Who was first conceived as an educational programme to slot into Saturday evening schedules.
Viewers discovered in the first episode that the Doctor was not a human, but an alien who travelled through time in his time and space machine - a Tardis - disguised as a police call box.
Later, when Hartnell left the series to be replaced by Troughton, he was written out by "regenerating" the Doctor.
At the end of a battle with the deadly Cybermen, the Doctor announced that his old body was beginning to "wear out" and he collapsed onto the floor of the Tardis, where special effects made the character change into his second form - played by Troughton.
Later it was explained that the Doctor was a Time Lord from the planet Gallifrey, and the process of regeneration was something that happened to all Time Lords 12 times before they finally died.