What every Doctor Who regeneration says about each Doctor's era

Tomorrow sees the final bow of the Eleventh Doctor, as Matt Smith regenerates into Peter Capaldi. But "The Time Of The Doctor" figures to be more than just this incarnation's last hurrah – like so many regeneration stories before it, the Christmas special is a chance to define just who this particular Doctor is, once and for all.

The fundamental appeal of a regeneration story is really a practical one: Such stories allow the show to continue after the departure of its star. There's no particularly requirement for any narrative or thematic significance beyond that, and indeed not all of Doctor Who's regenerations have been accompanied with all that much fanfare. As long as an old Doctor leaves and a new Doctor arrives, the change itself doesn't have to be the result of anything more serious or compelling than a bump on the head – which is precisely what happened to the poor Sixth Doctor in the wake of Colin Baker's firing.

But at their best, the regeneration stories offer the closing arguments for their Doctors, revealing just what each particular incarnation cares about most and what each is willing to die for. There's even an opportunity to fashion the Doctor into a kind of tragic hero, as each Doctor confronts his fatal flaw and comes to understand why it may well be time to become someone new.

And so, just as I used the occasion of the Tenth Doctor's demise to rank the regenerations – although I'll warn you right now that my opinions of some of the stories have changed quite a bit since the heady, carefree days of 2010 – the moment of the Eleventh Doctor's farewell offers a chance to explore what previous regeneration stories set out to accomplish, and what they reveal about each Doctor's era, both in-universe and behind the scenes.

The First Doctor: "The Tenth Planet" (1966)

What every Doctor Who regeneration says about each Doctor's era

"The Tenth Planet" isn't really about saying goodbye to William Hartnell; rather, it's about ensuring the show's very survival. Hartnell's health had deteriorated to the point that he could no longer continue in the starring role, and so producer Innes Lloyd and script editor Gerry Davis came up with the brilliant, frankly bonkers idea of having Hartnell turn into Patrick Troughton. Even then, there was no guarantee that Hartnell would be well enough to make it through his final adventure, and indeed his illness forced him to miss the taping of the third episode at the last minute. Planning for just such a contingency, Davis had minimized the Doctor's role throughout the story so that the character could be written out on short notice.

The cumulative effect is a farewell to the First Doctor in which the First Doctor barely appears. The Doctor has only 92 lines in the whole adventure, compared to 212 in his penultimate story, "The Smugglers." The Doctor effectively delegates his responsibilities to his companions, as Ben Jackson gets to play the man of action – hardly unheard of for male companions in the Hartnell era, admittedly – while Polly emerges as the most vocal critic of the Cybermen and their cold, unfeeling logic. The Doctor gets in a couple fierce rebukes of these new monsters, but he spends an awful lot of the story standing on the sidelines.

As such, while "The Tenth Planet" is best understood for its valiant efforts to resolve the greatest behind-the-scenes crisis in its history (at least until the show was cancelled) while telling a very good base-under-siege story, it's harder to see this as a fitting capstone to the Hartnell era. Still, given all that we've subsequently learned about the Doctor, I'd actually suggest that it's oddly appropriate for this Doctor to simply grow old and fall ill. Unlike all his successors, this is the one Doctor who was actually born, who naturally aged from child to old man, with an entire life tucked in between those points that we're unlikely ever to see. A relatively natural death is fitting for this Doctor, and his recognition that "this old body of mine is wearing a bit thin" plays as an acknowledgment that he hung onto his original body a little too long. In that sense, it's right that there's no longer a natural place for him in "The Tenth Planet."

The Second Doctor: "The War Games" (1969)

What every Doctor Who regeneration says about each Doctor's era

Like "The Tenth Planet," Patrick Troughton's final adventure is more about setting up the show's future than celebrating its present. By the end of the Second Doctor's tenure, viewer interest was flagging, and the incoming production team decided to reduce the budget and shake up the show by reformatting the series as an Earth-set, UNIT-centric show. "The War Games" then must contrive a way to deposit the Doctor in that new status quo, and it accomplishes this through the Second Doctor's trial, exile, and de facto execution at the hands of his own people, the Time Lords. That enforced change in appearance only happens because Troughton had decided three seasons was enough; if he had decided to stay on, "The War Games" would need only the quickest of rewrites to account that hypothetical change.

Indeed, the Second Doctor's fate is only really dealt with in the final episode; the preceding nine entries in the story simply represent the biggest, most epic adventure of the Second Doctor's tenure. The gigantic scale of the story means there's plenty of room for Troughton to show off the various sides of the Doctor – his compassion, his cunning, his comedy, even his cowardice – but there's not much sense that this story represents the end of the line for the Doctor, at least not until the Time Lords are mentioned. When the Doctor's own people do enter the story, nothing is ever the same again. The Doctor is terrified of the Time Lords' godlike wrath, and he would rather leave his companions Jamie and Zoe behind on an alien planet than risk putting them in harm's way by letting him join his last, desperate escape attempt. Multiple times in the last episode, the Doctor attempts to escape his people's clutches, although the sense is that he's more trying to keep up appearances for his friends than anything else. He knows there's nowhere left to run, and so he's finally forced to account for his actions. He does so successfully, but only at the cost of this particular incarnation and his companions' memories of him.

As grim an ending as this is for the Second Doctor, it's not entirely inappropriate. I'm reminded of the description of the Eleventh Doctor—who is, thanks to Matt Smith, the closest match for Troughton's Doctor among all his successors—in "The Day of the Doctor" as "the man who forgets." That seems an appropriate description for the Second Doctor as well, who spent his existence relishing the wonders of the universe with almost childlike glee. The First Doctor at least acknowledged that he and Susan someday hoped to return to their home planet, but the Second Doctor was just as happy to keep on adventuring forever. His trial at the end of "The War Games" forces him to defend his traveling as something more than mere frivolity. The Second Doctor was always more serious than he is given credit for, but it's only at the very end that he is forced to recognize that himself. Playtime is over, even if he hates to admit it.

The Third Doctor: "Planet of the Spiders" (1974)

What every Doctor Who regeneration says about each Doctor's era

This is really the first proper regeneration story — and not just because this is the first story in which the term "regenerating" is actually used. This is the first time in the history of Doctor Who in which its star departs with the show's future secure. Unlike "The Tenth Planet" and "The War Games," "Planet of the Spiders" is Doctor Who working from a position of strength, and so the only real goal here is to provide a fitting swansong for Third Doctor Jon Pertwee, producer Barry Letts, script editor Terrance Dicks, and the particular vision of the show that they forged over five seasons.

As such, this adventure pioneers many elements that recur in subsequent regeneration stories. The story forces the Doctor to confront his fears and admit the terrible cost of his hubris, of his greed for knowledge. Old friends are acknowledged: Richard Franklin returns to redeem the disgraced Mike Yates, while an unseen Jo Grant helps set the plot in motion when she mails the Doctor the Metebelis crystal he gave her in "The Green Death." The nature of regeneration itself is considered, specifically in the context of Buddhist philosophy; there's rather obvious significance to Cho Je's observation in the first episode that "The old man must die and the new man will discover to his inexpressible joy that he has never existed."

Admittedly, most of these elements are rather underdeveloped. Mike Yates and the Doctor pick up where they left off, with no onscreen discussion of the former's treachery. In theory, the first episode most clearly demonstrates the danger of the Doctor's thirst for knowledge when his psychic experiments on Professor Herbert Clegg result in the man's death, but this event is quickly forgotten. All the pieces are there for this to be one of the most powerful regeneration stories. The fact that it isn't somewhat reflects how the priorities of television storytelling have changed between 1974 and 2013, but that isn't the most immediate reason why this adventure doesn't live up to its potential.

Ultimately, "Planet of the Spiders" is more concerned with saying goodbye to Jon Pertwee and Barry Letts than it is the Third Doctor. That's why Pertwee is allowed to pilot every cool vehicle in existence during the second episode's notoriously pointless chase sequence, and it's why Letts – who co-wrote, directed, and produced the story – injects so many Buddhist elements into the plot, whether they make sense or not. As Terrance Dicks himself argues on the story's making-of documentary, the Doctor's lines about his greed for information is more an indication of Letts' fascination with Buddhist thought than it is a particularly well-considered critique of the Third Doctor. I'm inclined to be a little more charitable than Dicks on that one. Because of the humiliation of his exile, the Third Doctor always felt his innate superiority more than most Doctors, and so many of his adventures with UNIT are driven by his (usually justified) belief that he knows better than everyone else. His admission that he stole the Metebelis crystal is a necessary acknowledgment that he sometimes gets it wrong, that there are rules that even he must abide by, even if it means facing a gigantic, super-intelligent spider in a radiation-soaked chamber. If that doesn't seem like an entirely apt summation of all the Third Doctor stood for… well, at least the attempt is there.

The Fourth Doctor: "Logopolis" (1981)

What every Doctor Who regeneration says about each Doctor's era

Unlike Jon Pertwee, Tom Baker didn't have the luxury of leaving with his most iconic production team, whether you consider that to be Philip Hinchcliffe and Robert Holmes or Graham Williams and some combination of Anthony Read and Douglas Adams. New producer John Nathan-Turner and new script editor Christopher H. Bidmead had restored much of the Fourth Doctor's seriousness after years of mounting silliness, and his most somber story is his departure. "Logopolis" is most commonly noted for its funereal tone; more than any other regeneration story, it feels like the end of an era, and Baker brings to every scene the full weight of his seven long years in the role.

It can feel strange to see such a consistently melancholy Fourth Doctor, and it's a far cry from the manic clown that first appeared way back in "Robot." And yet, whatever else the story's problems, it's difficult to imagine how else this Doctor could have met his fate. The Fourth remains the most alien of the Doctors, and "Logopolis" succeeds most in making a Time Lord's regeneration feel otherworldly and unknowable. The presence of the Watcher is crucial to this effect, and Baker ably conveys the idea that the Doctor is moving resignedly towards his doom. For eons, the Fourth Doctor has treated the universe as a playground, but what always made this incarnation work is that he always knew when it was time to be serious. In the case of "Logopolis," that time simply occurs about three minutes into the story, as an ancient alien quietly prepares for the end.

The Fifth Doctor: "The Caves of Androzani" (1984)

What every Doctor Who regeneration says about each Doctor's era

Really, what more is there to say about "The Caves of Androzani"? More to the point, what more is there for me to say? It's my favorite story starring my favorite Doctor, and I'm tempted to just leave it at that. Still, in terms of the present discussion, "The Caves of Androzani" should be recognized for how purposefully small its stakes are. The setting amounts to little more than a nasty little resource war between a corrupt establishment and a wronged psychopath, and the Doctor himself barely takes an interest in it beyond the first episode. That's because the Doctor and his companion Peri are dying from almost the opening scene of the story, even if it takes them a little while to learn that fact.

Spectrox toxemia is a brutally appropriate cause of death for the Fifth Doctor, considering he and Peri only contract the disease after idly brushing against some raw spectrox. It's a careless mistake, but one that is demanded by the Fifth Doctor's entire worldview. He is the most idealistic of the Doctors, the one who sees the cosmos as a grand adventure best approached with open arms and a brave heart. He assumes the spectrox is harmless because, on some level, he needs to give everything the benefit of the doubt. The universe has failed to live up to his high standards so, so many times – most famously, as he stood among countless corpses at the end of "Warriors of the Deep," he observed, "There should have been another way." As such, the Doctor's ultimate rejection of the violence around him in favor of finding the cure represents that other way, even if the death toll in "Caves of Androzani" is just as high as that in "Warriors of the Deep." There's only one innocent in the Doctor's final adventure, and he gives his life to save hers.

In doing so, the Doctor also earns a measure of redemption for the death of Adric. The Fifth Doctor cannot help but be defined by the companion that he failed to keep safe, and it's only fitting that "Adric" would be this incarnation's last word. It's been pointed out that the Doctor has likely already begun his regeneration cycle long before he makes it back to the TARDIS; when he cries "I'm not going to let you stop me now!" in the greatest cliffhanger in the show's history, he might be talking as much to himself as he is to the man pointing a gun at him. Compared to other Doctors, the Fifth can sometimes seem woefully naïve, even feckless in his willingness to let events unfold around him. But when push comes to the proverbial shove, there are no lengths he won't go to in order to save Peri. In his final actions, the Fifth Doctor reveals the man he always was, and he offers one last example for the rest of the cosmos to live up to.

The Seventh Doctor: "Doctor Who: The Movie" (1996)

What every Doctor Who regeneration says about each Doctor's era

Much like his predecessor, the Seventh Doctor's regeneration is really just a tiny part of his successor's debut. Circumstances were more favorable for Sylvester McCoy to return for the regeneration than they had been for Colin Baker, which is why the Seventh Doctor gets an entry here and the Sixth Doctor does not. Still, the Seventh Doctor's appearance in the TV movie constitutes little more than a glorified cameo, comprising only ten lines and a few dozen words. It's a nice, well-intentioned nod to the show's past – even if was ludicrously misguided from a storytelling perspective, as the old Doctor's introduction and immediate death could only serve to confuse new viewers – but it's a rather perfunctory farewell for the Seventh Doctor himself.

And yet, there's a certain weird thematic logic to this Doctor dying because he forgets to check the TARDIS scanner and wanders into the middle of a gang war, leading to Dr. Grace Holloway's botched exploratory surgery. Considering all the endless schemes and manipulations that defined this Doctor, it's ironic that his regeneration would be the result of a tactical blunder and human error. After eons of outwitting the cosmos, chaos finally catches up to the Seventh Doctor. When he briefly wakes up on the operating table, he finds himself in a situation beyond his control, one that he failed to account for. The pointlessness of the Seventh Doctor's death can be seen as the point, even if the makers of the TV movie didn't intend it that way.

All that said, if some hypothetical regeneration story had featured the Seventh Doctor defeating some unimaginably powerful godlike being by enact his most fiendishly complex masterplan, one that ultimately required him to sacrifice himself… yes, I could see how that probably would have been a slightly better way for Time's Champion to bow out. Ah well, can't have everything.

The Eighth Doctor: "The Night of the Doctor" (2013)

What every Doctor Who regeneration says about each Doctor's era

The Eighth Doctor's long-awaited regeneration story is effectively "The Caves of Androzani" in miniature. Like the Fifth Doctor's departure story, "Night of the Doctor" shows the Doctor desperately trying to save the life of a young woman he barely knows; hell, both stories prominently feature the Doctor crashing a spaceship into a desert planet. The divergence is that Peri is the Fifth Doctor's friend and companion, whereas the gunship crew member Cass hates the Doctor from the first moment she learns just what he is. As bleak as "The Caves of Androzani" is, it still leaves room for the Doctor to be the Doctor. There is still the potential for him to triumph, to emerge victorious. The universe is a much darker place by the time of "The Night of the Doctor," and the Eighth Doctor cannot even sacrifice his own life to save that of another. In terms of what the story is setting up for "The Day of the Doctor," the crucial moment comes when Paul McGann observes that the universe doesn't need a Doctor anymore. A warrior is now required.

Just before he regenerates, the Doctor acknowledges Charley, C'rizz, Lucie, Tamsin, and Molly, the companions whose adventures were recorded in the Big Finish audios. And without treading too far into spoiler territory, some of the names on that list didn't fare much better than Cass. All Doctors are touched by tragedy and death, but the Eighth Doctor in particular lost so many people that he cared about so deeply. If we're allowed to acknowledge reality here, that's probably because the Eighth Doctor's adventures were almost exclusively chronicled in spinoff media, where there tends to be more latitude to kill off companions than there is on the televised, more explicitly family-friendly version of Doctor Who. But still, throughout all media, the Eighth Doctor consistently defined himself in contrast to his predecessor. After the endless stratagems of the Seventh Doctor, the Eighth explicitly tried to embrace once again the more romantic – in multiple senses of the word – side of this grand adventure.

His decision to become a warrior in "The Night of the Doctor" may stand as the final rejection of this effort, but remember what the Sisterhood of Karn tells him: By then, he has already been dead for minutes. If that's the case, then the last living act of the Eighth Doctor is his decision to remain on the crashing ship, pleading with Cass to put aside her fear and her hatred. It's a futile gesture, perhaps, but it says everything you need to know about this Doctor.

The War Doctor: "The Day of the Doctor" (2013)

What every Doctor Who regeneration says about each Doctor's era

John Hurt's brief tenure as the Doctor leads directly into the events of "Rose," thanks to Christopher Eccleston's digitally inserted eyes. The War Doctor's regeneration is there to close final big gap in the Doctor's chronology, leaving as little question of further hidden Doctors as there can be, given Who fans' proclivity for wild, unfounded speculation. It's likely significant that he regenerates immediately upon his departure (again, assuming no future writer crowbars in subsequent adventures between the dematerialization and the cut to the TARDIS interior). After all, the Eighth Doctor chose to regenerate into a warrior, and so the War Doctor's tenure must necessarily end upon the Time War's conclusion. Whether that's down to the magic of the Karn sisterhood, the Doctor's own buried wish to shed his warrior persona, or just general thematic appropriateness is something to be interpreted by the individual viewer.

But let's not forget the War Doctor's own comment on his imminent regeneration, as he acknowledges that his body – which, given his youthful appearance in "The Night of the Doctor," has visibly aged more than any other Doctor except the First – is wearing a bit thin. That specific callback to William Hartnell's line in "The Tenth Planet" is one last meta-textual reminder of the War Doctor's purpose in "The Day of the Doctor." In his frequent criticisms of his successors, he serves as a proxy for all the classic Doctors, particularly the older, grumpier incarnations like Hartnell's and Pertwee's. Even though this Doctor theoretically comes after Paul McGann (and Peter Davison, for that matter), he's played as an earlier Doctor, with little patience for the affected youthfulness of his future selves. As such, it's a nice touch that his death so closely recalls that of the First Doctor; they're even standing over the TARDIS console in roughly the same position when their regenerations begin.

The Ninth Doctor: "Bad Wolf"/"Parting of the Ways" (2005)

What every Doctor Who regeneration says about each Doctor's era

There's a bunch of ways to approach the Ninth Doctor's death, and the meaning of his regeneration feels different in the wake of "The Day of the Doctor." I don't mean that in terms of the altered history of the Time War, at least not directly, because that might suggest this Doctor's sacrifice – his very existence, even – doesn't matter so much when his most formative memory is a lie. But I'd argue that that misses the true significance of what "The Day of the Doctor" has to say about the Ninth Doctor, namely that the choices of that war-scarred, traumatized incarnation helped rebuild the shattered psyche of the Doctor, allowing those incarnations that came after him to choose a different path. The Ninth Doctor himself chooses that better way when he refuses to unleash the Delta wave to defeat the Daleks at the cost of every life on Earth.

He calls himself a coward, but that's just because his self-loathing allows the Daleks to get inside his head. It might seem that he's no longer capable of making the hard choices that ended the Time War, but that assumes that the hard choice is always the most violent one. The Ninth Doctor refuses to have any more blood on his hands, and for that he is rewarded with the arrival of Bad Wolf Rose. I'm pretty sure all this subtext was always there, but I'll admit that it helped me considerably to understand just where all this was going. The Ninth Doctor's entire existence was really one long regeneration, an attempt to reclaim his identity after all the terrible actions that he was forced to commit during the Time War. The show asked viewers to fill in rather a lot of narrative blanks to understand all that back in 2005 – and I doubt anyone foresaw precisely how the show would ultimately fill in those blanks – but "Parting of the Ways" is a more fitting end than I initially gave it credit for.

Of course, the Doctor doesn't die at the hands of the Daleks; rather, he absorbs the power of the time vortex in a last-ditch effort to save Rose's life. That means he joins the Fifth Doctor (and arguably the Eighth) as an incarnation that sacrificed his own life to save a companion. Unlike those two previous incarnations, who died trying to save people they had only just met (although the Fifth knew Peri rather better than the Eighth knew Cass), the Ninth Doctor's entire life was defined by his relationship with Rose. He needed to meet someone like her so that he could learn how to live with joy and a purpose once more. For a Time Lord, it's only a tiny extra step to learn how to die with joy and a purpose as well.

The Tenth Doctor: "The End of Time" (2010)

What every Doctor Who regeneration says about each Doctor's era

I've warmed considerably to "The End of Time" since it first aired in 2010. Selective memory helps here; in particular, "Part One" could be chopped down to about ten minutes without sacrificing much of the story. But once the not inconsiderable padding is removed, what's left is the departure story that offers the most explicit meditation on what regeneration means to the incarnation about to meet his demise. His conversation with Wilf in the first episode is a beautifully written scene, one that cuts to the heart of just why the Tenth Doctor fears regeneration or death – assuming there's a difference – so much. At the time, I found his perspective rather irritatingly selfish, one that seemed to implicitly put down the incoming Doctor before he had even arrived. My opinion didn't change all that much when the circumstances of his fate finally snap into focus, and he is dearly tempted to abandon Wilf to his fate in the radiation chamber because, as he angrily cries, "I could do so much more!"

The thing is, though, that these moments of selfishness are entirely right for this particular Doctor. David Tennant's incarnation is capable of a whole lot of things, but stoic resignation isn't really one of them, at least not immediately. His melancholy and his impotent rage merely externalize and clarify the same kind of internal conflict the Third Doctor was likely going through in "Planet of the Spiders." It's hard to blame the Tenth Doctor for not wanting to die, especially when, unlike so many of his predecessors, it all happens slowly enough for him to realize exactly what he's getting into.

Part of what makes the regeneration portion of "The End of Time" work is that, well, it really has nothing to do with the rest of "The End of Time." I don't mean to dismiss the rest of the story entirely, but the story of the Master Race and the Time Lords' return is Russell T. Davies at his most absurdly, even goofily larger-than-life. The Tenth Doctor could have died stopping the Time Lords, and that might have worked well enough, but the fact of the matter is that the Doctor saves the universe (or at least significant chunks of it) all the time. There's nothing wrong with epic stakes, but they don't really reveal what makes the Doctor special. The Doctor is the Doctor not because he would die to save everything; he's the Doctor because he would gladly die to save the life of one old man. The fact that this particular Doctor momentarily hesitates is true to his character, but it doesn't undermine the beauty of that ultimate sacrifice, and all the ones that came before it — give or take the odd bump on the head.