Doctor Who

1. Doctor Who (BBC, 1963-89, 2005-Present) It happened around 1979: A villain bent on distorting time and improving his own standing at the expense of humanity has trapped the Doctor (Tom Baker). Erudite bordering on the effeminate, this evil agent regards the smiling, jovial Doctor with a mixture of bemusement and contempt.

"You," he says to the Doctor, "are dangerously clever."

And that's it. That's the sum total of the premise behind "Doctor Who," the British sci-fi series that has proven itself to be the most durable, most charming, most altogether fun excursion into the unknown on the dial to date. The Doctor's superpower is simply that he's an incredibly smart man, a "Time Lord" with an ambiguous past who uses an antiquated police call box (the TARDIS, or Time And Relative Dimension In Space) to surf through the ages like an astrophysicist Laird Hamilton. Armed only with his wits (and a sonic screwdriver), often accompanied by a female companion (the audience's gape-mouthed stand-in), the Doctor plunks himself into impossible circumstances and then finds a way out. Aliens want to vaporize Earth and then sell off the chunks to the highest galactic bidder? He'll deal with it. A villain wants to steal the Mona Lisa so he can sell the six duplicates to unsuspecting art collectors? The Doctor will buzz himself into da Vinci's pad and write "This is a fake" in black magic marker on each of the drafts. Wanna see the literal end of the world, five billion years from now? He's got your first-class ticket.

To call "Who" a science-fiction fable is a bit of a mislabeling: Because of his kinetic, restless whims, he can drop himself (and the viewer) into any genre. Horror. Fantasy. Romance. Current Doctor David Tennant has even expressed interest in adding a musical to the series' 725 installments.

More than 800 years old, the Doctor–we never learn his true name, hence his working title–has the ability to re-generate himself up to twelve times when critically wounded. The '60s played host to Doctors who were older, sophisticated and charged gamely through cardboard sets; the '70s employed Baker, who adorned himself with a free-flowing scarf that rivals the fabric of any Todd McFarlane cape ever drawn; the fabulously deranged resurrection of the series in 2005–after a 16-year hiatus–brought us Doctors Nine and Ten, with Number Eleven (Matt Smith) on call for 2010.

With his regenative lives running out, it's possible "Who" could finally disappear into the black hole of time. If it's truly the end, it will stand as sci-fi TV's most deliriously imaginative creation. But if anyone can figure out the perscription for TV immortality, it's the Doctor. Watch This: "The End of the World," a jolly 2005 introduction to the retooled franchise and Christopher Eccleston's manic interpretation of the Doctor.