It’s the return, after awhile, of a great, perhaps the greatest, holiday tradition, by which I refer of course to the “Doctor Who” Christmas Day special. I don’t know what else you could have imagined I meant.

With Russell T Davies, who revived the ancient British series from suspended animation in 2005, back as showrunner and a brand-new Doctor, the Fifteenth, at the controls of the TARDIS, this represents, like any good solstice celebration, a birth and a rebirth, or, in Whovian terms, a regeneration. The three Davies-penned specials that preceded it this year — the first to be distributed by Disney+ and, more significantly, made with Disney money — brought back fan-favorite Tenth Doctor David Tennant as the Fourteenth Doctor (still very much of a piece with the Tenth) and reunited him with Catherine Tate’s Donna Noble.

The last of those specials, “The Giggle,” introduced Fifteenth Doctor Ncuti Gatwa without, as has been the custom, killing off his predecessor, through the invention of “bigeneration.” Together, Fourteen and Fifteen defeated Neil Patrick Harris’ exquisitely evil Toymaker, after which Tennant’s Doctor settled down in happy retirement with Donna and her family. This year’s splendid Christmas Day special, “The Church on Ruby Road,” gives us our first full meal of Gatwa as the pilot of the TARDIS and introduces new companion Ruby Sunday (Millie Gibson), quite in the sparky mode of Billie Piper’s up-for-anything Rose Tyler, Davies’ first created companion.

Decisions are made about the lives of fictional characters for extratextual as well as internal reasons, and the Doctor and Donna specials were crafted from an attitude of happiness and goodwill that seems to be the hallmark of the coming season. To reintroduce the beloved Tennant only to kill him again would have been cruel, hardly the way to embark on a new era. But to leave him in a garden, retired, enjoying a meal was a gift to the characters and those of us who love them.

Did it matter that this all required the writing of new rules that contravened years of canon? There are some, I suppose, who believe that a show like this, with 39 seasons over 60 years, can be smushed into some sort of canonical consistency. But “Doctor Who” has never been shy about rewriting the rules, or particularly bothered with consistency, or even sense, except within the strictures of any particular episode. And Davies’ approach has always been more poetical than technical.

Not every Christmas Day special has been equally Christmassy, but there is usually at least some bit of decoration or dusting of snow or passing reference to the holiday. (Davies introduced Tennant’s Tenth Doctor with “The Christmas Invasion”; there were killer Santa robots.) Steven Moffat, who oversaw Matt Smith’s Eleventh and Peter Capaldi’s Twelfth Doctors, most embraced the theme, with episodes referencing Charles Dickens, C.S. Lewis and Santa Claus; “The Church on Ruby Road,” which is set primarily in the days leading up to Christmas 2023, gives us a baby left in the snow at a church door and goblins up on the rooftop who first present as evil elves — which is to say, one is wearing a Santa cap.

There’s a nutty streak to Davies’ creations that in practice demonstrates that a strange idea well executed creates its own reality — as in a production number in a floating goblin pirate ship, which makes no sense apart from the fact that it’s weird, delightful (in its horrifying way) and works.

At the same time, the new “Who” feels streamlined for speed and simplicity. The Thirteenth Doctor’s multiple traveling companions — she (Jodie Whittaker) was the “fam” Doctor — have been reduced to the singular Ruby Sunday, who is as colorful as her name, eager for adventure and unfazed by alien oddness. The TARDIS, which could get very messy inside — it changes along with the Doctor — has been cleaned up into a deluxe version of its white-with-circles, 20th-century original.

“Doctor Who” may be the most analyzed series in science fiction, and commentators have had many critical things to say about it over the years — which is only natural given a show that changes its spots every so often — some informed by deep knowledge and some by simple prejudice.

For my part, I’ve never met a Doctor I didn’t like, and going back over the Christopher Eccleston, Tennant, Smith, Capaldi and Whittaker years in light of Gatwa’s bow, I find no reason to alter that opinion or bar him from the pantheon. To be sure, not every episode has been equally good and some story arcs I found more rewarding, or more enervating, than others. But each new Doctor brings something unique to the role.

Although it isn’t hard to find internet commenters or YouTube pundits attacking Davies — or Moffat or Chris Chibnall, for that matter — for ruining the show with various casting or thematic choices, there seems to have been less controversy over casting Gatwa, who is Scottish Rwandan, Black and queer, than Whittaker, as the first female Doctor, perhaps because some of those naysayers have already peeled off from the show, which has embraced representation and inclusion for quite some time. (That the specials included a trans character and another in a wheelchair especially set teeth gnashing.) Of course, there’s no way to declare that the Doctor shouldn’t be Black that isn’t out-and-out racist, and so many of these comments are couched in attacks on the producers for wokeness or virtue-signaling.

Indeed, it would have been very surprising — whoever the showrunner, given the series’ 21st-century history — if after Whittaker the show had cast another white dude. But Gatwa is here not on account of his color or sexual orientation, but because he’s young, fit and sexy, and radiates joy. That isn’t to say things might not get tangled and dark as the story goes on — that the Doctor and Ruby are both foundlings would appear to be setting up the season’s main thematic business — but “Ruby Road” is pure exhilarating adventure. Gatwa is a dancing Doctor, a singing Doctor, a running and jumping Doctor, a muscular Doctor, a fashionable Doctor, a Doctor who shows a little skin, and may quite possibly prove to be a feeling Doctor.

It will be fun finding out.

How to watch: Disney+