'He doesn't like endings,' but ultimately Whovians don't mind

Spoiler alert: You watched Saturday night's "Doctor Who" mid-season finale, right? If you missed it, or are intending, one day, to Netflix the series and DON'T want any inkling of what happened in the episode, stop reading now. We don't divulge information that hasn't been already well-publicized. But we know even the faintest of spoilers can get you riled up like a Dalek on the trail of a sonic screwdriver. Read at your own risk.

Amy and Rory couldn't travel with The Doctor forever. Not that fans suspected they could - the Doctor's past includes many companions. But now we have to wait until the special Christmas episode, possibly beyond that, to see the next stop on the epic TARDIS hitchhike.

In Saturday’s “Doctor Who” mid-season finale, “change” and “endings” were as thick as the fog that attends the sneaky, predatory weeping angels. For a show about an alien who travels through time saving Earth and thwarting evil across the universe, the message got a bit heavy-handed at times. It was almost as if executive producer Steven Moffat was trying to prepare himself, the Doctor and the audience for the inevitable.

Even Matt Smith (the eleventh man to play the Doctor) was emphasizing that theme in an interview before last month's New York City season premiere screening.

“The show is about change,” he said. “Like Steven likes to say, it can never be predictable, it can never be cozy – It’s got to feel like it’s sort of marking new territory, I think, every season.”

But why belabor the point? This is a television show that for nearly 50 years has established the fact that the characters on the show are always coming and going - including the titular main character, the Doctor (who?) Even relatively new fans (and certainly, American fans fit that bill) of the show have gleaned that time travel is a limited engagement.

That started in 1966, when the show’s original Doctor, William Hartnell, needed to retire due to health issues. The show's producers devised a clever plan to transition to a new actor, Patrick Troughton, in the main character role.

The alien nature of the Doctor provided the fix: As a species known as a Time Lord, the Doctor can regenerate instead of dying in the traditional sense. Once regenerated, the Doctor is essentially a new person: he retains memories from his previous life but has a fresh personality.

This prevents a classic Dick York/Dick Sargent quandary where a new actor is installed and no one is supposed to notice the change. Even better, when an actor takes over the Doctor’s role, they aren’t trying to mimic their predecessor’s performance, which allows them to put a unique spin on the character all while adhering to the show’s canon.

"Doctor Who" fans, or “Whovians,” are unique among television show fandoms in that each fan can point to a favorite version of the Doctor without also having overwhelming disdain for any particular actor in the role. A popular T-shirt cheekily states, “You never forget your first Doctor,” and it’s spot-on; a Whovian’s fan identity is typically established with the first incarnation of the Time Lord (or his companion) they fall in love with.

By comparison, Trekkers can debate about who their favorite captains from the many iterations of "Star Trek" were, but there generally isn’t much disagreement over which specific version of Kirk they love the most (sorry, Chris Pine).

Newer "Who" fans might have joined the party with the debonaire tenth Doctor, David Tennant, but many thirty-somethings within the fandom have a particular fondness for Tom Baker. Baker, with his iconic scarf of many colors and sandy blond afro, was the fourth Doctor and the first whose tenure received an extended run in the U.S. on PBS in the late 1970s (although selected episodes of third Doctor, Jon Pertwee, did air stateside prior to that).

For decades, “Doctor Who” targeted families and garnered solid ratings in the United Kingdom before it was suspended in 1989 due to dropping viewership. Russell T. Davies revived the series with the ninth Doctor, played with edgy fury by Christopher Eccleston, in 2005 following a 16-year absence (save for a 1996 TV movie).

Tennant’s Shakespearean flare helped establish a quirkier vibe and romantic core for the show, while Smith’s bow-tie-clad turn has transformed the show into an American pop culture staple. The current season’s September 1 premiere earned 1.6 million viewers, a series best since the show moved from Syfy to BBC America in 2009. The numbers represent a 23 percent increase in viewership from the show’s 2011 premiere, and the sixth season was the most downloaded show on iTunes in the US last year.

The Doctor’s companions, too, are expected to be swapped out with some frequency. Following the Ponds/Williams’ TARDIS retirement, the Doctor flew off with their daughter - also his wife - River Song. The comfort of seeing a familiar face helped lessen the blow for fans: River Song has crossed paths with the Time Lord many times over the last five seasons of "Doctor Who."

Certainly, Karen Gillan, the actress who played Amelia (Amy) Pond, wasn’t entirely ready for the end of this companionship.

After learning her character’s fate in this weekend’s episode, “The Angels take Manhattan,” she sank into sadness.

“I was crying for pretty much the entire two weeks we were shooting that episode. In between takes. Just, in life. Little things were setting me off. I was sensitive,” she said at San Diego Comic Con during the Doctor Who panel in July.

In a pre-panel interview, fellow companion Arthur Darvill (who played Rory Williams, Amy Pond’s husband) said he has enjoyed being one-half of the first married couple on the TARDIS as well as the longest-running modern companions.

“We're so close to it at the moment and I think it will take a few years to be able to actually realize what we've done personally, but also kind of how it is on the show," Darvill said. "Hopefully we've added something quite exciting to it."

Fans have known since March of this year that Amy and Rory would leave the Doctor's side and newcomer Jenna-Louise Coleman will end up riding shotgun in the TARDIS. Fans may remember her as the crashed spaceship survivor from the first episode of this season.

“If you look at the history of the man, he picks up hot chicks and travels around the universe for two years and then goes, ‘eh, see you later, Rose,” joked Smith. The character of Rose Tyler established the possibility of a companion who was also a love interest - she captured the heart of the tenth Doctor, who still somehow managed to end up with two more companions before his regeneration.

“Doctor Who” executive producer Caroline Skinner admitted in September that she wasn’t “quite ready” to see Gillan and Darvill leave the show. When asked about Smith’s departure, she joked, “We’re never going to lose Matt!”

“I think that everyone, including the U.S. fans, also seem to really get and love the fact that 'Doctor Who' is kind of all about change and change is its essence, and it must never stop moving because that way the show won’t really be at its full strength,” Skinner said.

And yet, there is a big change in the near future that poses a challenge beyond finding a new companion or actor for the Doctor to regenerate into. According to show lore, a Time Lord can only regenerate 13 times, and Smith is currently the eleventh incarnation.

“They’ll have to invent something then where they can keep it going because why would we want to stop making it?” said Smith. “I’ll be old news by then, so I don’t know, really, but it’s a show that isn’t afraid of change and I embrace that.”