An undated handout photo made available by the BBC showing the Eleven Doctors, from left, William Hartnell, Patrick Troughton, Jon Pertwee, Tom Baker, Peter Davison, Colin Baker, Sylvester McCoy, Paul McGann, Christopher Eccleston, David Tennant and Matt Smith. "Doctor Who" is turning 50 and the BBC is throwing a broadcasting blowout for the sci-fi show, which began with little fanfare and few expectations on Nov. 23, 1963 but is now one of its biggest hits and major exports. (AP Photo/BBC)

"Sometimes I have these extraordinary dreams. I dream that I'm this adventurer, this daredevil. A mad man! The Doctor, I'm called... "

The Doctor in Doctor Who: Human Nature (in which he has to take human form in as a history teacher in an English private school just before World War I to evade a deadly enemy)

"People assume that time is a strict progression of cause to effect. But actually, from a non-linear, non-subjective viewpoint, it's more like a big ball of wibbly-wobbly, timey-wimey... stuff."

The Doctor in Doctor Who: Blink (in which the Doctor, stuck in 1969 London without his blue box, communicates through DVD Easter eggs with the woman who must rescue him)

"I'll be a story in your head, but that's okay, because we're all stories in the end. Just make it a good one, eh? Because it was, you know. It was the best. A daft old man who stole a magic box and ran away. Did I ever tell you that I stole it? Well, I 'borrowed' it. I always meant to take it back. Oh, that box, Amy, you'll dream about that box. It'll never leave you. Big and little at the same time. Brand-new and ancient and the bluest blue ever. And the times we had, eh? Would have had... never had. In your dreams, they'll still be there. The Doctor and Amy Pond and the days that never came."

The Doctor in Doctor Who: The Big Bang (in which the Doctor must reboot the universe but erase his existence in the process)

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Fiftieth anniversaries can be such tricky things in popular culture, can't they?

I kid, of course, because they are such rare things. Most shows, movie franchises, even careers, have far shorter lives.

Now we are in the midst of a run of a few notable 50ths, with 2012 being the 50th anniversary of the James Bond film franchise, 2016 being the 50th anniversary of the Star Trek franchise, and the year just past having been the 50th anniversary of Doctor Who, a longtime British mass favorite which has become a global cult show since it came back in 2005 following a 16-year hiatus. I decided to wait until after the annual Doctor Who Christmas special, a holiday institution in the UK now near simulcast around the world, to assess the anniversary, for the special also marked one of the show's not infrequent shift changes from one iteration of the Doctor (ready portrayal by an actor) to another. Having wrenched my back over the holidays, the wait was longer than I'd planned, especially with several political pieces pushing into the queue last week.

Matt Smith and David Tennant, the Eleventh and Tenth Doctors, answer fan questions about Doctor Who's 50th anniversary.

The James Bond 50th anniversary was carried off in spectacular fashion, with the celebratory feature film, Skyfall, turning out to be one of the top 10 films of all-time in global box office, carrying off the wonderful trick of blending callbacks to the franchise's legendary past with a story moving the character and his world from the present into a future which is nonetheless a brilliantly updated version of the past. The Star Trek 50th anniversary is the subject of some trepidation with the latest film, 2013's Star Trek Into Darkness -- second in the rebooted film series -- though a major hit also turning out to be a conceptual misfire.

The verdict on Doctor Who's 50th anniversary year? Good, but too sparse. The final season for Matt Smith's Doctor got short-shrift by being cut in half, with the first half shown in 2012 and the second in the anniversary year 2013. And the most important shows and specials got too caught up in grasping for solutions to the showrunner's overly involved plotting.

But the spirit was certainly there, and that is what always carries Doctor Who. And the BBC did a good job of providing ancillary materials, books and music and retrospective discs, around the 50th anniversary.

The weekend before Thanksgiving saw the 50th anniversary episode of Doctor Who, in which Matt Smith's Eleventh Doctor teamed up with arguably the most popular of them all, the Tenth Doctor played by Shakespearean star David Tennant, whose fan girl following can be a bit daunting to some critics and an earlier quasi-Doctor played by John Hurt. The most popular of the earlier Doctors, Tom Baker's Fourth Doctor, also had an enigmatic role. It was quite good.

Just before that, the BBC put out a special docudrama, An Adventure in Space and Time, on the show's 1963 beginnings through the tenure of the first Doctor. The show humorously and rather poignantly pointed up what a departure Doctor Who was for the BBC at the time. One established executive is shown advocating "more Dickens" for the Saturday night time slot. Ah, yes, but of course. The show was conceived and championed by outsiders, from the new Canadian programming director Sidney Newman (Brian Cox) to the network's first female producer Verity Lambert (Jessica Raine) and the Indian immigrant director Waris Hussein (Sacha Dhawan). Naturally, they had to have a somewhat forbidding older Brit playing the lead in David Bradley's heartfelt rendition of William Hartnell, who unknown to the producers at first suffered from an increasingly debilitating version of arteriosclerosis affecting his ability to remember his lines.

Next up, the show's annual Christmas special featured the regeneration of the current Doctor into the next Doctor. Which is to say from young Matt Smith to not-young Peter Capaldi.

For those who don't know, incidentally, the Doctor is an alien traveler through time and space from the lost planet Gallifrey, home to the late race of Time Lords, an explorer who spends a lot of time defending Earth -- and in particular, naturally, Britain -- from various threats in between his adventurous travels into the past and the future of many worlds all around the universe. He looks like a human being, but has two hearts and is extremely long-lived, being at least 900 years old as we met him back in 1963, when his adventures were first telecast by the BBC on the otherwise dirge-filled day after the assassination of John F. Kennedy. The Doctor, armed only with a sonic screwdriver, is essentially non-violent and eschews guns. But things don't always turn out that way.

He's usually accompanied by at least one human companion, usually an attractive young woman. But since Doctor Who began as a children's show and is still officially that, the romance angle is downplayed. A genius, the Doctor is a polymath of science and history. What he doesn't know, languages, for example, can be filled in by the tech in his time ship, the TARDIS, which means Time and Relative Dimensions In Space. The ship, an exemplar of the small-is-beautiful doctrine, is famously "bigger on the inside than the outside," its camouflaging "chameleon circuit" permanently stuck on presenting the TARDIS as a blue police phone box from 1960s London.

Yes, the trademark tongue-in-cheek British humor is baked into Doctor Who, as is a great deal of wit and heart and magic and wonder.

The Doctor, who never says his name, doesn't age so much as he changes, "regenerates" actually, from one iteration of the Doctor to another. He is thus at once ancient and relatively youthful, sometimes very much so depending on the age of the actor playing him. This of course allows not infrequent recasting. There have been 11 (or 12, depending upon your perspective) Doctors up till the latest Christmas special, in which the 20-something Matt Smith version changed at the end into the 50-something Peter Capaldi version.

I have to say that I found this Christmas special, though good, too busy and not holiday-spirited enough compared to the past Christmas specials, which have are a major cultural institution in the UK. Current Doctor Who showrunner Steven Moffat, who took over in 2010 after Russell T. Davies successfully rebooted Doctor Who in 2005, had too many dangling ropes of plot to resolve before Matt Smith's Eleventh Doctor changed in to Peter Capaldi's Twelfth.

And as a result, some of the show's biggest mysteries got some pretty short-shrift solution in the Christmas special.

But it's still all good.

There are two basic ways to watch Doctor Who.

One is by following, or trying to follow, all the increasingly complex twists and turns of Moffat-era plotting and how it relates to the apocrypha of the show going back to the '60s.

The other is by being generally aware of all that but focusing on the performance, the with, the heart, the insights, and the magic of each episode. Since this is not Star Trek, which I've watched from the very beginning, and my experience with Doctor Who -- aside from occasionally seeing its early years incarnation on public television from time to time -- goes back to the 2005 revival, I prefer the latter approach.

Without giving away too many spoilers -- or, put another way, without recapping Moffat's rather hasty resolutions to plot twists dating back to 2010 -- the Christmas special worked, just, as a way of ending Matt Smith's tenure and bringing on Peter Capaldi. But it was perhaps the least Christmassy of all the Christmas specials.

And I felt it gave rather short shrift to Smith, especially in comparison with the two-part extravaganza that ended David Tennant's tenure. Like many, I was a huge fan of Tennant when took over after Christopher Eccleston revived the part in 2005. Smith, then a relative unknown in his mid-20s who tends to take an unusual-looking still photo, seemed an odd choice at first to take over for Tennant, who was endless dextrous with drama, comedy, romance, action, and loads of expository and informative dialogue, generally with whatever twist was needed to take the edge off. Or to put one on.

But Smith won me over in the first 10 minutes of his first episode, with the eyes and attitude of an ancient soul backlighting his youthful antics. He proved a truly inspired choice.

Now we have Peter Capaldi. While Tennant was a very well-established actor when he took over the role, a budding star on television and a respected stage actor in his mid-30s, Capaldi is even more well-known and well-established.

Now 55, Capaldi is one of Britain's leading character actors. And he is quite famous for one role in particular, that of the spin doctor and political enforcer Malcolm Tucker in the hit TV series The Thick of It, which spawned a film called In the Loop. His Tucker is an elegantly profane Scot, based according to some on Tony Blair's former communications director Alastair Campbell. As we see from the clip here, it's not likely that Capaldi's Doctor will operate much like Tucker, though he'll probably have a harder edge.

Peter Capaldi's famed incarnation as spin doctor/political enforcer Malcolm Tucker is unlikely to bleed too much into his role as the new Doctor.

What actually makes Capaldi's casting something of a challenge is not so much his identification with indelible Malcolm Tucker but his having already played a major role in the Whoniverse, in the great Children of Earth miniseries version of spin-off series Torchwood.

There he played John Frobisher, permanent secretary of the Home Office, the perfect civil service mandarin, a good man who follows the logic of situation, position, and institution as he is thrust into the lead role in dealing with a shadowy alien race which once secretly inveigled twelve orphans from a compliant British government of the '60s in exchange for a vaccine against a super-flu and is now back for much, much more. Capaldi is brilliant in this villainous, tragic role which did so much to make 2009's excellent Children of Earth easily the high-water mark for the hit-or-miss Torchwood. The producers will have to come up with a clever reason why the new Doctor looks exactly like this major character.

But I have little doubt they can do just that.

So we've seen now in two successive years -- first with James Bond, now with Doctor Who -- that the Brits know how to celebrate 50th anniversaries of their cherished cultural products.

Which raises a question. Do Americans know how to do this?

Star Trek's 50th anniversary, about which I'll have a lot more to say, is in 2016. But the series, which underwent a very successful movie reboot in 2009 with new versions of the iconic cast created by a convenient change in the timeline, seems like it's in need of reboot once again, and shows no current sign of being ready for its 50th anniversary.

2013's Star Trek Into Darkness was a sizable hit and did better worldwide than did 2009's Star Trek, thanks to a greatly expanded marketing effort. But even though the production budget was pumped up for the sequel, it did substantially less well than the 2009 movie, which reintroduced Star Trek with such pace and flash and dazzle that any conceptual problems were simply overwhelmed.

Not so in Star Trek Into Darkness, which began promisingly as a terrorism-oriented piece around the brilliant Sherlock star Benedict Cumberbatch as a disgruntled Starfleet officer only to devolve into a nitwit reworking of perhaps the greatest of all Star Trek films, Star Trek: The Wrath of Khan. With the lily white Londonder Cumberbatch as former South Asian warlord and 20th century genetically engineered superman Khan Noonien Singh! What?

The misstep poisoned the well around the film, especially with reboot director J.J. Abrams repeatedly insisting before the movie opened that Cumberbatch was not playing Khan.

Now Abrams, who notoriously said he hadn't watched Star Trek when he was younger because it was "too philosophical," is off making the new Star Wars. Only Bob Orci of the original Abrams-derived writing group remains for the next picture in the series.

While the studio says the next movie will be released in 50th anniversary year 2016, it still has no director attached and no release date.

Needless to say, I don't have a good feeling about Star Trek's 50th anniversary year so far. Since I vividly remember watching the very first Star Trek episode on September 8, 1966, this concerns me.