The phrase "the most wonderful time of the year" generally refers to the holiday season, but for fans of "Doctor Who" it means something else entirely.

WhoVians know that this is the time of year when the Doctor, the hero of the long-running British sci-fi series, reappears on our planet in the Tardis, with all new episodes of their iconic show airing. And this year, there is much more to celebrate than our newly reborn heroes being ready to take the helm of the iconic blue spaceship and time ship.

The year 2023 marks the 60th anniversary of "Doctor Who," which first aired on the BBC in November 1963. The station is pulling out all the stops to make this a fitting celebration of this major milestone for the Gallifreyan Time Lord. But before the new season kicks off with the first of three anniversary specials on November 25, there are a few things to remember about the Doctor's latest adventures.

When it was announced that Jodie Whittaker would be leaving "Doctor Who" after three seasons as the 13th Doctor alongside showrunner Chris Chibnall, fans around the world began speculating who would be next. It was eventually revealed that Nuchi Gatwa of "Sex Education" would replace Whittaker in May 2022.

However, when the 13th Doctor regenerated for his final special, it was David Tennant's face on the screen, not the award-winning Scottish actor of Rwandan descent.

Tennant is not the only one returning to "Doctor Who" in the new season. He will appear on screen in three specials titled The Star Beast, Wild Blue Yonder, and The Giggle, alongside Catherine Tate, who played Donna Noble, one of the Tenth Doctor's most beloved companions. And behind the scenes, Russell T. Davies, who played the role from the series' 2005 relaunch until 2010, has returned to run the show.

Tennant is best known as the 10th Doctor, but after Whitaker's final episode, it was revealed that her former "Broadchurch" co-star would also become the 14th Doctor. There is a precedent for this thanks to Tom Baker, the fourth Doctor, playing the Curator in the 2013 special "The Day of the Doctor," in which Tennant, Matt Smith, and John Hurt played different incarnations of the Doctor. The Curator (understood to be the future regeneration of the main character) told the 11th Doctor that he would revisit some "old favorites" after telling him he would never forget a face.

But the idea of a past actor playing a new version of the Doctor is not new. According to Doctor Who: The Eighties, by David J. Howe, Mark Stammers, and Steven James Walker, series co-creator Sidney Newman had the second Doctor, Patrick Trouton, in 1986. He wanted him to return to the show for one season and then regenerate into a female Doctor.

So if David Tennant is both the Tenth Doctor and the Fourteenth Doctor, what would happen to Nucci Gatwa? After the Anniversary Special, he will appear as the 15th Doctor, starting with the show's annual holiday special titled "The Church on Ruby Street."

When this episode airs on December 25, he will be the key to the kingdom in the new season, scheduled to air in 2024. More precisely, Gatwa will have a sonic screwdriver.

But how on earth will it go from 14 to 15? Since the filming of the new season, the producers have done incredibly well to keep the details under wraps. However, Davis did give a modest warning in a BBC press release. The showrunner said, "Nutsy's path to the 15th Doctor is full of mystery, fear, robots, puppets, danger, and fun."

Along with a new Doctor (and an old new Doctor), "Doctor Who" will also have a new streaming home. In the UK and Ireland, it will be available on BBC iPlayer as usual. For international viewing, however, it will be available exclusively on Disney Plus.

However, if you want to see David Tennant's first film as the Doctor, or any of Russell T. Davies' other contributions to the franchise, you will need to look elsewhere. Whovians in the home country of the UK can access over 800 episodes in the Whoniverse on the BBC iPlayer, but for the rest of us it's a bit more complicated.

Previously, the majority of "Doctor Who" was available for streaming on Prime Video. Later, this fan-anticipated series made its way to Max. Unfortunately, only "New Who" (episodes from 2005 onward) is available on Max. To watch episodes of Classic Who dating back to the beginning of the broadcast, you will need to subscribe to BritBox. Of course, as for the latest specials, they can only be viewed on Mouse House.

So far, we have mostly dealt with the real-world side of "Doctor Who. But the biggest question left has to do with the story: why isn't Donna Temple-Noble, who is reunited with the Doctor, dead?

In the Season 4 episodes "The Stolen Earth" and "Journey's End," we saw Donna become Doctor Donna and absorb all of the Time Lord's knowledge to save the day from the diabolical Dalek leader, Davros. But because her human brain cannot handle thousands of years of information, the Doctor is forced to erase her memory of the adventure against her wishes before her mind burns out.

Later, in the two-part special "End of Time," which marks the end of Tennant's regular tenure as the Doctor, Donna unwittingly helps an old friend fight the Master. But just as she is about to regain her memory, a telepathic pulse that the Doctor has installed as a failsafe is triggered, rendering her unconscious and safe.

Since Donna cannot recall her time with the Doctor at the risk of a mental explosion, does the appearance of the 14th Doctor jog her memory? Or can a new adventure with a somewhat familiar adventurer leave her unscathed? Of course, these questions will not be answered until the 60th anniversary episode premieres, but we are eager to know exactly how this reunion is possible.