Regeneration (Doctor Who)

Regeneration, in the British science fiction television series Doctor Who, is a biological ability exhibited by Time Lords, a race of fictional humanoids originating on the planet Gallifrey. This process allows a Time Lord who is old or mortally wounded to undergo a transformation into a new physical form and a somewhat different personality. The process has been used ten times to introduce a new actor for the role of the main character of the program, known as the Doctor. The current Doctor is played by Matt Smith, who followed David Tennant in the role.

Conceptual history

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The First Doctor collapses prior to his regeneration (from The Tenth Planet, 1966).

The role of the Doctor had been played by William Hartnell at the programme's inception in 1963. However, by 1966, it was increasingly apparent that Hartnell's health was deteriorating and he was becoming more difficult to work with. By the time the second story of Season 4, The Tenth Planet, was greenlighted, the decision had been made to replace Hartnell. Script editor Gerry Davis proposed that, since the Doctor had already been established as an alien, the character could die and return in a new body. Producer Innes Lloyd further suggested that the Doctor could do this "renewal" regularly, transforming from an older man to a younger one. This would allow for the convenient recasting of the role when necessary. The process itself was modelled on LSD trips with the experience being like the "hell and dank horror" of taking the drug.

At the conclusion of The Tenth Planet, the First Doctor collapses from apparent old age and exhaustion, having commented earlier that his body was "wearing a bit thin". Then, before the eyes of his companions Ben and Polly, and the viewing audience, his features shift into that of the Second Doctor, played by Patrick Troughton.

On screen this process was not called "regeneration", but a "renewal". In The Power of the Daleks, the Second Doctor's first story, the Doctor draws an analogy between the renewal and a caterpillar turning into a butterfly.

In the About Time reference series Lawrence Miles and Tat Wood note that the officially licensed magazine, Doctor Who Monthly, stated in a "Matrix Data-Bank" column in 1982 that its readers should not confuse the "regenerations" of later incarnations with the "rejuvenation" of Hartnell into Troughton.

It was not clear initially whether the renewal was a natural ability of the Doctor's as opposed to a process initiated by technology. In Power, the Doctor describes his renewal as a function of his TARDIS time machine, stating that "without it, [he] couldn't survive."

When Troughton left the series in 1969, the Doctor was renewed again, but this time it was forced on him by the Time Lords at the conclusion of The War Games, where it is referred to as a "change of appearance". Once again, this suggested that it was a superficial physical change, not one of personality, although Jon Pertwee's portrayal of the Third Doctor also differed quite substantially from Troughton's. In addition, this change is treated as a punishment rather than a natural process – the Second Doctor protests, "You can't just change what I look like without consulting me!"

It was only at the end of the Third Doctor's era, in Planet of the Spiders (1974), when Pertwee's Doctor turns into Tom Baker's Fourth Doctor, that the change is finally called "regeneration" and is explained as a biological process that occurred when a Time Lord's body was dying. It is also stated that following the regeneration the Doctor's brain cells would be shaken up and his behaviour would be "erratic" for a time, something that would be true for most subsequent regenerations.

As the series continued, more aspects of the regenerative process were introduced, but the basic concepts of regeneration as accepted by fans of the series today were only firmly established in the final scene of Planet of the Spiders. This notwithstanding, it is now generally accepted by fans (from an in-universe perspective) that the "renewal" of the First Doctor into the Second and the "change of appearance" of the Second Doctor into the Third were both part of the same process of regeneration. This has been further supported by on-screen dialogue that has explicitly enumerated the number of times the Doctor has regenerated and has counted the First-to-Second "rejuvenation" among them (these episodes have included Mawdryn Undead (1983), The Five Doctors (1983), the 1996 television movie, and more recently episodes such as The Next Doctor, The Eleventh Hour and The Lodger.

Transitions

The Fourth Doctor regenerates into the Fifth Doctor (from Logopolis, 1981 and Castrovalva, 1982)

The regeneration "effect" was accomplished during the series' original run from 1963–1989 primarily through the use of video mixing. Originally, the plan was to have Hartnell collapse at the end of The Tenth Planet with his cloak over his face, which would then be pulled back to reveal Troughton in the next serial. However, vision mixer Shirley Coward discovered and took advantage of a malfunction in the mixing desk which allowed Hartnell's image to be overexposed to the point of almost whiting out the screen, then fading back in to reveal Troughton's face. This also meant that the regeneration scene could take place with both actors at the conclusion of The Tenth Planet, and Troughton was accordingly signed up to participate.

Subsequent regenerations retained essentially the same method, with or without additional video or make-up effects. The transition from the Fourth to the Fifth Doctor used an additional make-up effect representing a transitional form known as the Watcher, but aside from this, other regenerations in the original series run simply mixed the image of the incoming actor on top of the outgoing one. The transition from the Seventh to the Eighth Doctor in the 1996 television movie took advantage of the higher budget and modern computer animation technology to "morph" the features of Sylvester McCoy into those of Paul McGann.

With the exception of the transitions from the Second to Third and the Eighth to Ninth Doctors, each regeneration was shown on-screen, with the previous incumbent in the role symbolically "handing off" the character to the next. The Second Doctor was never seen to actually change into the Third, simply fading off into darkness at the end of The War Games and then stumbling out of the TARDIS, already regenerated, at the start of Spearhead from Space (1970).

The regeneration of the Sixth Doctor into the Seventh is the only time that a single actor took on the roles of two incarnations of the Doctor. Colin Baker declined the invitation to film the regeneration sequence at the start of Time and the Rani (1987) due to the circumstances in which the BBC dismissed him from the role. As a result, Sylvester McCoy had to don his predecessor's costume and a blond curly wig, lying face down, with the mixing effect to the Doctor's "new" features occurring as he was turned over.

The 2005 series, which revived the programme after a 16-year hiatus, began with the Ninth Doctor already regenerated, with no explanation given as to the circumstances behind the change (although dialogue within the debut episode, Rose indicated the change had recently occurred). In the documentary series Doctor Who Confidential, producer Russell T Davies explained his reasoning that, after such a long hiatus, a regeneration in the first episode would not just be confusing for new viewers but also lack dramatic impact, as there would be no emotional investment in the character before he was replaced. The regeneration of the Ninth Doctor into the Tenth at the end of "The Parting of the Ways" (2005) was seen, and also used computer effects to morph Christopher Eccleston into David Tennant. In the episode of Doctor Who Confidential accompanying the episode "Utopia", it was stated that the production team had decided that this would be a common effect for all Time Lord regenerations (the Master's in this case) rather than having a regeneration sequence chosen on a whim by the director. A similar sequence was used for David Tennant's regeneration into Matt Smith in "The End of Time", though this time the effect on the TARDIS is much more violent, possibly due to the Doctor's attempts to fight the regeneration or the severity of the radiation poisoning that brought about the process to begin with. This regeneration effect was also used in "The Impossible Astronaut" when the Eleventh Doctor is shot twice, albeit with a more wispy effect. However in this case the full transition is not seen as the Doctor is shot again fatally before completing the process. It was later revealed that this was actually a robot impersonating the Doctor. The effect was used again at the end of the following episode "Day of the Moon" when a mysterious girl also regenerated (although her new incarnation is not depicted), and in "Let's Kill Hitler" when Mels (Nina Toussaint-White) is shot and regenerates into River Song (Alex Kingston). The same effect appears when Donna Noble (Catherine Tate) and the Tenth Doctor's spare hand together spawn a Doctor-Donna hybrid in "Journey's End".

In the series

The exact mechanism that makes regeneration possible is not stated in the television series, but it is generally assumed in the spin-off media that the ability to regenerate may be linked to what is known as the "Rassilon Imprimatur", the symbiotic nuclei of a Time Lord that bonds him or her to a TARDIS, and allows his or her body to withstand the molecular stresses of time travel (The Two Doctors, 1985). In "The Christmas Invasion" (2005) it was stated the regenerative cycle generates a large amount of energy that suffuses the Time Lord's body. As demonstrated by the Tenth Doctor, in the first fifteen hours of regeneration this energy is enough to even rapidly regrow a severed hand. In the moments following his regeneration into his eighth incarnation, the Doctor possessed enough physical strength to batter a steel door completely off its hinges. In Let's Kill Hitler River Song is able to repel bullets after regenerating.

It is first stated in The Deadly Assassin (1976) that a Time Lord can regenerate twelve times before dying (thirteen incarnations in all). There are exceptions to this rule, however; when a renegade Time Lord known as the Master finds himself at the end of his regenerative cycle, he takes possession of the body of another person to continue living (The Keeper of Traken, 1981), although he was using the Source of Traken to bind his mind to the body. It may be that the Time Lords also have the ability to circumvent the limit – in The Five Doctors (1983) the Master is offered a new cycle of regenerations by the High Council in exchange for his help. The fact that the Master is inhabiting a non-Gallifreyan body at the time implies that it is possible to grant them to a non-Gallifreyan, albeit one inhabited by a Time Lord mind (although River Song is shown to have the ability to regenerate with altered DNA that has similarities to Time Lord DNA, due to Amy Pond's proximity to the TARDIS whilst pregnant with her. In "The Sound of Drums" (2007) the Master is revealed to have been granted a new body by the Time Lords during the Time War with at least two new regenerations. Non-Gallifreyans are also seen to regenerate in Underworld (1978) and Mawdryn Undead (1983), but with adverse side effects. In Mawdryn Undead these appear to be the result of mishandling stolen technology, but in Underworld they are implied to be the inevitable result of limited technology that reinvigorates, rather than transforms, the subject's appearance (in this case, the Minyans, with whom the Time Lords shared much of their technology), thereby regenerating 'the body, not the soul'.

The BBC's Series 4 FAQ suggests that now the Time Lord social order has been destroyed, the Doctor may be able to circumvent the limit on regenerations; it says: "Now that his people are gone, who knows? Time Lords used to have 13 lives." In Death of the Doctor (a 2010 The Sarah Jane Adventures serial), the Eleventh Doctor responds to a question from Clyde Langer by saying he can regenerate "507" times. Early news reports, before the episode was broadcast, suggested he would say there is no limit to the number of regenerations. Writer Russell T Davies explained in an interview with SFX that the line was not intended to be taken seriously and is instead a commentary. He insisted that the "thirteen lives" rule was too deeply entrenched in the viewer consciousness for his throwaway line to affect it.

In the Fourth Doctor story The Brain of Morbius, the Doctor participates in a mental ‘duel’ with another Time Lord. The machine to which their minds are connected begins to project the faces of the "losing" contestant’s regenerations in chronologically descending order. As the Doctor is overpowered by Morbius, the images change successively to those of the third, second and first Doctors, then eight further faces appear. The narrative does not definitively assert that these are past incarnations of the Doctor rather than of Morbius; other evidence from the series suggests they cannot be. The Doctor himself has numbered his regenerations on several occasions, each time intimating that the William Hartnell incarnation was the first. For example, it is explicitly stated by the Fifth Doctor in Mawdryn Undead that he has eight incarnations left, and in The Five Doctors Peter Davison's Doctor (introducing himself to the First Doctor) says that he is the fourth regeneration, meaning that there have been five of him. Again in The Five Doctors, the First Doctor refers to himself as the "original" and in Doctor Who, Paul McGann, with Sylvester McCoy on screen, states both "A Time Lord has thirteen lives and The Master'd used all of his." and "In all my travels through space and time, and nearing the end of my seventh life...". Most recently, in The Lodger, after the Eleventh Doctor showed Craig who he was, he pointed to his face and said, "Eleventh".

With regeneration also comes a change of personality. This is likely a side effect of the process of complete physical transformation, which includes an alteration of the brain chemistry and synaptic organisation. The viewing audience sees this most often and most dramatically in the differing quirks and personality traits of the Doctor's various incarnations. However, it appears that the Doctor's core personality traits of heroism and intolerance of injustice are still retained. The Doctor also sometimes goes through a period of physical and psychological instability (which has included partial amnesia, temporary manic depression, walking into a tree and on one occasion an act of physical violence against his companion) following a regeneration, but it is not clear if this is true of all Time Lord regenerations, particularly since the Doctor's regenerations tend to happen due to stressful and violent situations. Regenerations have been known to fail, and may require assistance, technological or otherwise, or a period of recovery to successfully complete the process. The Brain of Morbius suggests that Time Lords other than the Doctor may experience difficult regenerations, since the Sisterhood of Karn had been supplying them with an "elixir of life" that could assist the process.

In some cases, future potential incarnations can achieve independent, though temporary, existence. In Planet of the Spiders, a Time Lord, K'anpo Rinpoche, creates a corporeal projection of a future incarnation which has such an existence under the name Cho Je until he regenerates into that incarnation. The Valeyard, a "distillation of the Doctor's evil side, who could potentially exist between the Doctor's twelfth and final incarnations", appears in The Trial of a Time Lord (1986) opposite the Sixth Doctor; the Valeyard is offered the Doctor's future regenerations which would "make his potential existence concrete". Another example is "The Watcher", who repeatedly appears to the Fourth Doctor in Logopolis (1981), and ultimately merges with him as part of his regeneration into his fifth incarnation.

The Time Lords' ability to change species during regeneration is referred to in the television movie by the Eighth Doctor in relation to the Master. This is supported by the implication by the Daleks that the First Doctor's apparently human appearance was not his true form (The Daleks' Master Plan, 1965) and the Fourth Doctor's Time Lady companion Romana's regeneration scene in Destiny of the Daleks (1979). In that scene Romana demonstrates an apparent ability to "try on" different bodies from a number of different species during her regeneration, before settling on a final, humanoid form which physically resembles Princess Astra of Atrios (see discussion below).

While explaining the process of regeneration to Rose at the end of "The Parting of the Ways", the Ninth Doctor suggests that his new form could have "two heads", or even "no head", although it is unclear if he is merely joking. In the 2005 Children in Need special, which takes place immediately after, the newly regenerated Tenth Doctor, while examining his new body, makes a point of checking that he has two arms, two legs and two hands, implying that regenerations can sometimes result in physically deformed or non-humanoid forms; whether this is also a joke is not clear. In the second part of The End of Time (2010), the Eleventh Doctor also enumerates eyes, ears, hands, fingers, and legs, and after feeling his hair, even wonders for a moment if he has changed sex. (In a later episode, "The Doctor's Wife," the Doctor refers to another Time Lord, the Corsair, having been both male and female in various incarnations.)

Whether or not Time Lords can recognise each other across regenerations is unclear from the television series. For example, in The Deadly Assassin an old classmate of the Doctor's, Runcible, is slow to recognise the Doctor in his fourth incarnation, and once he has, it then takes him a while to realise that his appearance has changed. However, in The Armageddon Factor (1978), Drax, another old classmate, recognises the Fourth Doctor immediately although they had not seen each other since the Academy (the Doctor takes a while to remember Drax, though). Shortly thereafter, in Destiny of the Daleks, the Doctor fails to recognise the yet-to-stabilize, newly-regenerated Romana. In The Twin Dilemma, the Sixth Doctor attributes old friend and fellow Time Lord Azmael's failure to recognise him to the fact that "I have regenerated twice since our last meeting." Yet in "The Sound of Drums" (2007) the Doctor states that Time Lords can "always" recognise each other, and recognises Harold Saxon as the Master on sight. However, in the mini-episode "Time Crash", the Fifth Doctor fails to recognise Tenth Doctor on first meeting, thinking he was merely "a fan" who has sneaked into the TARDIS.

It has been suggested in the series many times that regeneration is not guaranteed and can fail. After his cellular structure is decimated by the Metabelis crystals in Planet of the Spiders, the Third Doctor's regeneration requires "a little push" from fellow Time Lord K'anpo Rimpoche before it can proceed. As he succumbs to spectrox toxaemia in The Caves of Androzani, the Fifth Doctor says, "I might regenerate... I don't know... It feels different this time...". He then hallucinates, seeing his former companions encouraging him to survive, before the Master overwhelms them all, telling him he must die. The 1996 TV movie showed the Doctor's regeneration delayed for more than three hours, with the Eighth Doctor later remarking that the fact his Seventh incarnation was under anaesthesia at the time of his "death" could have "destroyed the regenerative process", and that he was "dead" prior to his regeneration. In many episodes, the Doctor doubts his own survival, though it is not always clear whether such statements refer to the death of only that particular incarnation. (The only time he makes a completely unambiguous distinction between these two scenarios – in The End of Time – he makes it clear that he regards regeneration as nearly as bad as death, because as he sees it, he dies and "a new man" walks away). In The Mind of Evil the Master points a conventional firearm at the Doctor and threatens to "put a bullet through both [his] hearts," while in "Forest of the Dead", Professor Song warns that electrocution would stop both the Time Lord's hearts, killing him. In "Turn Left"—which presents an alternative timeline—a UNIT member speculates that the Tenth Doctor is killed "too quickly for him to regenerate." In the first part of The End of Time, the Doctor tells Wilfred Mott that if he is killed before the regeneration can start, then it will fail.

In the Series 6 premiere, "The Impossible Astronaut", a future version of the Eleventh Doctor is shot twice by the titular astronaut and begins to regenerate. However he is then shot again and dies, showing that not only can he be killed before regeneration, but also while the change is taking place. (However, the later revelation, in "The Wedding of River Song" that what was shot was in fact a mechanical avatar of the Doctor and not the real person calls this into question.) Later, in the fourth episode of the series, "The Doctor's Wife", it was stated that Time Lords can potentially change gender during a regeneration, something which had never been confirmed before (although, at certain points during the show's history, female actors have been suggested as possible candidates to play the Doctor). In "A Good Man Goes To War" Madame Vastra explained how the Time Lords became what they became through billions of years of exposure to the Time Vortex. In the series 6 episode "Let's Kill Hitler" the Doctor was revived after death by River Song who used her remaining regenerations to do this.

The Doctor's regenerations

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The Fifth Doctor recuperates from his regeneration in the Zero Room (from Castrovalva, 1982).

As noted, the Doctor frequently experiences a period of physical and mental instability following regeneration and some post-regeneration experiences have been more difficult than others. The Fifth Doctor (in Castrovalva) begins reverting to his previous personalities and the Sixth Doctor experiences extreme paranoia, flying into a murderous rage and nearly killing his companion (The Twin Dilemma, 1984). The Eighth Doctor experienced amnesia as a result of post-regeneration trauma (the 1996 television film); uniquely, the Doctor was "not alive" at the time of this regeneration. The regeneration from the Ninth to the Tenth Doctor sees the Doctor unconscious for most of the next fifteen hours ("The Christmas Invasion"). In the series four finale of the revived series, "Journey's End", an injured Tenth Doctor manages to avert a full regeneration by channelling "excess regenerative energy" into his severed hand, allowing him to heal without changing form. The limb ends up developing into a half-human clone when Donna Noble touches it; the event, a "two-way" "Human-Time Lord Meta-Crisis", also gives Donna a Time Lord's mind. The Tenth Doctor learns of his impending demise in "Planet of the Dead"; in The End of Time, he laments that even if he survives using regeneration, the death of his current personality and attributes makes for something much akin to an actual death. His last words were "I don't want to go." As mentioned previously, in "The Impossible Astronaut" a future Eleventh Doctor is shot twice and begins to regenerate, but is shot again and killed before the process completes.

The TARDIS appears to assist in the regenerative process, as suggested by the second Doctor's statement to this effect shortly after regenerating from the First. This is reiterated by Jack Harkness' insistence that the Doctor be taken into the TARDIS having been shot by a Dalek in The Stolen Earth. Of the five occasions on which he has regenerated outside the TARDIS, one is forced on him by the Time Lords (Second to Third Doctor, The War Games), one requires a Time Lord to give the Doctor's cells a "little push" to start the process (Third to Fourth, Planet of the Spiders), one needs the TARDIS's "Zero Room", a chamber sealed from all outside forces, to help him recover (Fourth to Fifth, Castrovalva) one occurs a few hours after he has actually "died" (Seventh to Eighth, the 1996 television film) and the last he is killed before fully regenerating (Future Eleventh, The Impossible Astronaut). The Seventh to Eighth regeneration remains the only one that takes place significantly far away from the TARDIS, without any obvious interaction from other Time Lords and resulted in the Doctor suffering near-complete amnesia for nearly a day until an event inside the TARDIS triggers his memories to return. The future Eleventh Doctor is killed in mid-regeneration, showing he is vulnerable to death while regenerating and as such his need for the TARDIS may be for safety rather than aid. However it is later revealed that this regeneration was indeed a simulation since the Doctor who was shot was actually a Teselecta robot.

The Doctor's transitions:

1. First Doctor (William Hartnell): Frail and steadily growing weaker throughout The Tenth Planet, the Doctor collapses inside the TARDIS at the serial's end.
2. Second Doctor (Patrick Troughton): a forced "change in appearance" and exile to Earth by the Time Lords in the closing moments of The War Games.
3. Third Doctor (Jon Pertwee): radiation poisoning from the Great One's cave of crystals on the planet Metabilis 3 at the end of Planet of the Spiders.
4. Fourth Doctor (Tom Baker): fell from the Pharos Project radio telescope in Logopolis during an altercation with the Master and was assisted in the regeneration by a mysterious "in-between" incarnation identified as "The Watcher".
5. Fifth Doctor (Peter Davison): spectrox toxaemia poisoning, contracted near the start of The Caves of Androzani.
6. Sixth Doctor (Colin Baker): suffered unspecified injuries when the Rani attacked the TARDIS and caused it to crash land at the start of Time and the Rani.
7. Seventh Doctor (Sylvester McCoy): died in San Francisco during exploratory heart surgery by a doctor unfamiliar with Time Lord physiology, after being hospitalised for non-life threatening gunshot wounds in the 1996 television movie.
8. Eighth Doctor (Paul McGann): unknown cause of death.
9. Ninth Doctor (Christopher Eccleston): cellular degeneration caused by absorbing the energies of the time vortex from Rose Tyler, which she in turn had absorbed through the heart of the TARDIS in "The Parting of the Ways".
10. Tenth Doctor (David Tennant): radiation poisoning incurred while saving the life of Wilfred Mott in The End of Time. The poisoning "killed" this Doctor more slowly than other causes, allowing him to spend an unknown length of time visiting past companions.

Romana's regeneration

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Romana tries on several bodies for size until settling on the last one, played by Lalla Ward (from Destiny of the Daleks, 1979).

Romana's tongue-in-cheek regeneration scene in Destiny of the Daleks contrasts markedly with the Doctor's transformations. In the first episode of the serial, Romana undergoes regeneration, in the process trying out several different forms before choosing to adopt the appearance of Princess Astra, a character she encountered in a previous adventure (The Armageddon Factor).

Doctor Who television writer and script editor Eric Saward suggests in his 1985 novelisation of The Twin Dilemma (1984) that Time Lords can control the appearance of their next body if they trigger the regeneration voluntarily, but not if the regeneration is caused by death or injury. The Doctor Who Role Playing Game by FASA suggested that some Time Lords have a special ability to control their regenerations.

The fan reference book The Discontinuity Guide suggests that the various "try-ons" were projections of potential future incarnations like the K'anpo Rinpoche/Cho Je situation in Planet of the Spiders. Miles and Wood's About Time also mentions this along with theorising that the Time Lords had improved the technology of regeneration since the Doctor's time; Romana, being of a later generation than the Doctor, would therefore have finer control over the regenerative process in its early stages. Aside from the how of it, multiple attempts have been made in the spin-off media to explain the necessity for Romana's regeneration.

• In the short story "The Lying Old Witch in the Wardrobe" by Mark Michalowski, published in the Big Finish Productions anthology, Short Trips: Companions, unknown to the Doctor, Romana suffers damage due to exposure to the Key to Time. Just as she is about to regenerate, a humanoid manifestation of the TARDIS, jealous of Romana, traps her in a force field. It proceeds to pretend to be Romana, changing into different forms until finally becoming a double of Princess Astra. This manifestation is the one who appears in Destiny of the Daleks. Realising the error of its ways after that adventure, it releases Romana, but not before making the female Time Lord assume the image of Astra.

• The second explanation, which may or may not be consistent with the first, is given in the Gallifrey audio series. Gallifrey: Lies by Gary Russell reveals that Romana forced her own regeneration to prevent an ancient Gallifreyan evil called Pandora from gaining power over her (see also History of the Time Lords – Audio plays).

• The third explanation is in the Fifth Doctor audio story The Chaos Pool by Peter Anghelides, which states that the creators of the Key to Time re-disguised its final segment as Romana, which is why she changed and why she chose Astra's form. It is possible that the previous explanation was arranged by the Key's makers to facilitate this one.

• Finally, in 2011 television episode "Let's Kill Hitler", River Song is fatally shot and says she is trying to concentrate while regenerating so she can come out a particular dress size, indicating control over her physical form is natural to some Time Lords but nevertheless very difficult.

The Master's regeneration

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The Master regenerates

The Master has regenerated once on-screen in the 2007 series episode "Utopia". After being fatally shot by the insectoid creature Chantho, the Master regenerates from the incarnation known as Professor Yana, played by Derek Jacobi, into the current incarnation, played by John Simm. Before regenerating, the Master expresses desire to become "young and strong" like the Tenth Doctor. The effect used for the Master's regeneration, though similar to the Ninth, Tenth and Eleventh Doctor's, is notably brighter and more colourful, using an array of psychedelic colours.

Previously, the Master has been shown to possess non-Gallifreyan bodies in order to extend his life. The first was a Trakenite named Tremas in The Keeper of Traken and the second was a human named Bruce in the TV movie. In The Deadly Assassin it is stated that the Master had in fact used up all his regenerations, hence his decrepit appearance in that serial. He is in fact attempting to use the artifacts of Rassilon to obtain a new cycle, but the process would destroy Gallifrey, so the Doctor intervenes. In The Five Doctors the High Council of Gallifrey offers the Master, who is now possessing the body of a Trakenite, a new regeneration cycle in exchange for his help. Although there's no indication he actually received this new cycle, in "Utopia" he regenerates naturally and in '"The Sound of Drums" he indicates that he had been resurrected by the Time Lords to fight in the Time War, suggesting his life had indeed been extended.

In "Last of the Time Lords", the Master demonstrates that regeneration is not an automatic process (or, it is, but can be prevented by will), refusing to regenerate after being shot by Lucy Saxon, despite the Doctor's pleas. The Master returned in The End of Time, resurrected with the same body he died in. He later makes remarks bemoaning this fact, suggesting this was not intended.

Other regenerations

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Mel, half-human, half-Time Lord and the second incarnation of Melody Pond, regenerates in Let's Kill Hitler.

In the premiere of the 2009 spin-off series K-9, the original K-9 Mark I (Leeson) is reintroduced and destroyed, but subsequently revealed to have been installed with a "regeneration circuit". At this point, the traditional K-9 model "regenerates" into a more sophisticated-looking CGI model.

In "The Doctor's Daughter" (2008), the Doctor's DNA is used to create the titular "daughter" Jenny (Georgia Moffet), who displays many but not all Time Lord traits. In the episode's close, she is shot in the chest and appears to die. However, long after the Doctor and his companions have departed, she miraculously resurrects and expels energy from her mouth which, ambiguously enough, both resembles regenerative energy and the energy emitted by a planet-restoring plot device in the same episode. The question as to whether this is a true regeneration is left unanswered, since Jenny does not change her appearance.

In "Day of the Moon" (2011), a child (Sydney Wade) walks through a New York City alley at the end of the episode. When a vagrant asks of her condition, she explains that all is well, that she is dying, but she can fix it. She subsequently begins to regenerate in the style of the revived series (as with Eccleston, Tennant and Jacobi). In "Let's Kill Hitler", it is revealed that this child was Melody Pond and that she regenerated into a toddler (Maya Glace-Green). This form later matured into Amy Pond's best friend, Mels (Nina Toussaint-White), who again changed into the Alex Kingston form of Melody (River Song). In the aforesaid episode, post-regeneration, Melody is immune to a barrage of gunfire due to her surplus regenerative energy.

Transference of regenerative energy

In Mawdryn Undead (1983), it is first referenced that a Time Lord could transfer his regenerative life essence to another being. In that story, the Fifth Doctor is coerced by Mawdryn to give up his future regenerations in order to cure Nyssa and Tegan Jovanka from Mawdryn 's disease. Although, the transfer did not occur (due to the timely interference of The Brigadier) the Doctor stated that the consequence of the transference would be that he would sacrifice his eight remaining lives and cease to be a Time Lord. It is not until "Let's Kill Hitler" (2011) that such a transference is shown. In that instance, River sacrifices her own regenerative power in order to save the Eleventh Doctor. A major plot point of the 1996 TV involves the Master scheming to steal the Doctor's remaining regenerations for himself.

See also

• Time Lord#Physical characteristics

External links

• Rassilon, Omega, and that Other guy: Gallifrey Stuff – every fact about the Time Lords no matter how apocryphal