Planet of the Daleks episode 3 has been restored to colour for DVD by a combination of two different techniques: one based on computer matching between shots in the b/w episode and similar shots in the surviving colour ones, and another which can actually extract the original colour information from traces of the original colour remaining on the b/w films thanks to a quirk (usually a fault) in the telecine process. There was also a LOT of manual tweaking and colourising. The result is impressive to say the least. Unfortunately this was too expensive to be feasible for the other black-and-white episodes. The second process only was used on the first episode of Invasion of the Dinosaurs for DVD, with noticeably inferior results, and on the episodes 2-4, 6, and 7 of The Ambassadors of Death and episodes 2-6 of The Mind of Evil, with mixed results. Episode 1 of The Mind of Evil was manually recolourised using a different process.
William Hartnell's regeneration at the end of The Tenth Planet survives only as a clip that was shown on the children's programme Blue Peter.
The Beatles make a cameo appearance in the 1965 story The Chase, in which they're seen on the Time-Space Visualizer performing "Ticket to Ride" on their only ever appearance on the venerable UK chart show Top of the Pops in 1964. Originally, the plan was to have the actual musicians appear as themselves as old men in the future, but the idea was vetoed by Beatles' manager Brian Epstein. Ironically, the live footage used in the episode is all that remains of this performance, as said Top of the Pops episode was erased.
A print of the 1965 episode The Daleks' Master Plan: "Day of Armageddon" was returned by former BBC engineer Francis Watson in January 2004.
The format of the show's entire run before cancellation was a series of cliff-hanger adventure serials. Although, as originally conceived, the series would have only run for fifty-two episodes (i.e. one a week for a year), which would have made up one single extra-length serial. The series' format evolved out of this. Each of the Doctor's adventures would be told across several 25 minute episodes, with a cliff-hanger ending each one. Each "season" of the show would be broken into several stories, taking usually 4 to 6 episodes to play out — on-screen, each individual episode would begin with the title of the story, followed by the story's author, then what episode number of the story the audience were watching. This method of titling wasn't established until late in the third season; prior to this every episode was given its own unique title. There are no definitive official story titles for many of the earliest adventures, though semi-official ones have been consistently used on DVDs, books, etc.
When the series was first syndicated in the US, many stations did not show it in its original cliffhanger format. Instead, a "movie version", made up of all episodes of one adventure, but with the cliff-hanger endings edited out, would be shown. Since the number of episodes used to tell one story would sometimes vary (usually four episodes, but sometimes 6, 7, or only 2), the "movie versions" varied in length. Because of this, many stations showed the movie versions on weekends, in late-night or early-morning slots, where their schedules were more flexible.
One one occasion (Silver Nemesis in 1988), the "movie version" was shown in New Zealand at the same time that Episode 1 was aired by the BBC, marking one of the few instances of episodes premiering outside the UK.
A second rare instance of episodes premiering outside the UK was for "The Five Doctors" in 1983, which aired for Children in Need in the UK a day or two after the anniversary. In the US (and likely elsewhere in the world too), it aired on the actual anniversary on the 23rd.
On six occasions, past Doctor actors have to returned to the series as the Doctor in stories known as "multi-Doctor" stories, meaning that they feature multiple incarnations of the Doctor.
In 1973, the 10th-Anniversary story The Three Doctors saw William Hartnell and Patrick Troughton return to the role alongside Jon Pertwee.
In 1983, the 20th-Anniversary story "The Five Doctors" saw Troughton and Jon Pertwee return to the role alongside Peter Davison whilst Richard Hurndall played the First Doctor (Hartnell had passed away some years earlier) and Tom Baker appeared only in footage filmed for Shada, which was abandoned due to strike action.
Troughton reprised his role as the Second Doctor alongside Colin Baker's Sixth in The Two Doctors.
The 30th-Anniversary special, 1993's "Dimensions In Time", had five of the seven Doctors (William Hartnell and Patrick Troughton both gave it a miss, what with them being dead at the time).
Tennant returned to join forces with Matt Smith's Eleventh Doctor for the 50th Anniversary special "The Day of the Doctor".
With all the other previous doctors reappearing via archive footage and Peter Capaldi making a split-second cameo. Tom Baker also reappears as a Museum Curator implied to be a retired version of the Doctor from the future.
Asteroid 3325, a small main belt asteroid discovered in 1984, is named TARDIS after the Doctor's time/space machine.
Many actors have been considered for the role of the Doctor over the years but only Ron Moody has twice declined the role. He was first choice after Hartnell left but refused (as did Peter Jeffrey), and he also turned down the chance again in 1969 when Troughton left. Graham Crowden turned down the role after Pertwee and veteran British comedian Richard Hearne was also considered but rejected for insurance purposes. In the revived version, Bill Nighy came closest to assuming the role after Christopher Eccleston left but was rejected at the last minute in favour of David Tennant (Nighy amusingly blamed Tennant for being better-looking).
Bill Nighy was also in the running to play the Ninth Doctor, to the extent that some media sources inaccurately reported that he'd been given the role when Eccleston's casting was announced.
Jon Pertwee had incredible difficulty learning some of the technobabble that the Doctor is famous for, so the crew hid cue cards in the set. Pertwee would also write some of his lines in Biro on the TARDIS console.
The Celestial Toymaker received complaints that the character Cyril was based on the Billy Bunter character created by Frank Richards, whose lawyers were incensed. The BBC issued a statement saying that Cyril was merely a Bunter-like character.
The original pilot episode was rediscovered in 1978 in a mislabeled film can. After an archive purge by the BBC between 1972 and 1978, the film survived by chance and was originally thought to be Lost Forever.
When the BBC attempted to register the appearance of the TARDIS as a trade mark, the Metropolitan Police complained and they went to court. The judge decided that the image was more recognisable with Doctor Who, and the police had never actually used the Police Box as a brand for commercial purposes, so the BBC was allowed to register it.
The pilot episode of the series would have been the first transmitted edition had it not been remounted on the recommendations of BBC executives. It has been shown on television in the UK once, in 1991, and remains the only surviving episode from the 1960s held in its original unedited format.
When it became clear that failing health was affecting his performance and relationship with the cast and crew, William Hartnell, the first actor to play the Doctor, was asked to leave the show. Rather than cancel the successful series, the writers came up with the Doctor's ability to regenerate his body when he is near death, which allows for the smooth transition from one actor to another playing the role. Their first attempt to eject Hartnell from the show happened some time earlier in The Celestial Toymaker, where the Doctor was made invisible at one point in the story. The original intention was for the Doctor to come back played by a different actor as part of the Toymaker's games, but this was vetoed and it was Hartnell that reappeared.
Originally, the Doctor's time machine, the TARDIS, was to have a different appearance in order to blend in wherever and whenever it materializes due to its "chameleon circuit". However, it was realized that this constant changing of a regular prop would be too expensive, and so it was decided that the circuit would be permanently disabled due to the TARDIS' age, thus retaining the appearance of a 1963 Police Box. A few decades later, the in-story reason for why the Doctor didn't keep trying to fix the circuit was that he'd grown fond of the shape.
The name of the Doctor's time machine, the TARDIS, is short for "Time And Relative Dimension In Space". In later serials, this was changed to "Time And Relative Dimensions In Space" (Dimensions in plural), but the series revamp in 2005 has reverted to the singular usage.
Ian Marter, who played Surgeon Lt. Harry Sullivan, also wrote the novelizations of several Doctor Who stories.
Julia Sawalha auditioned for the role of Ace.
As William Hartnell's illness progressed, he started to have memory problems and often forgot his lines. Many unusual ad libbed lines in place of those scripted were passed off as part of the Doctor's character.
The distinctive TARDIS sound effect is officially classified as a piece of music and was created by rubbing the bass strings of a piano with a key.
Two reasons are given for the first episode of the first series series being repeated the following week: a) it aired the day after John F. Kennedy's assassination and as a result drew lower than expected audiences. b) there was a widespread power failure and the episode was not seen nationwide.
The series was originally devised as an educational program for kids, with co-creator Sydney Newman having no intention of featuring "bug eyed monsters." The first episodes featured cavemen. But when the Daleks were introduced, the attitude of the program was forever changed. Even so, the series continued to alternate between science fiction and purely historical stories for several seasons.
During the 1970s, series star Tom Baker and Ian Marter (who had played his companion Harry Sullivan) co-wrote and attempted to have a feature film entitled Doctor Who Meets Scratchman, which would have co-starred Vincent Price. When a copy of the script was discovered in John Nathan-Turner's archives, it turned out to consist of non-stop surrealism more reminiscent of the weirder episodes of The Avengers or The Prisoner than Doctor Who, making "The Mind Robber" look Mundane Dogmatic.
The series was in part inspired by the British Quatermass TV serials of the 1950s. In 1988, the show paid homage by referring to Quatermass in the 1988 serial Remembrance of the Daleks...where it's also implied that this episode takes place the day Doctor Who made its debut.
Quatermass was alluded to again in 2009's "Planet of the Dead".
In a weird but fitting piece of coincidence, David Tennant was starring in a modern day Live Episode remake of The Quatermass Experiment the day when he learned that he had been cast as the Tenth Doctor.
Although a number of televised spin-offs were considered throughout the course of the programme (including vehicles for the Daleks, for UNIT, and for the Jago and Litefoot characters from the Tom Baker serial The Talons of Weng Chiang), only one was ever produced before the show's 2005 return — "K-9 and Company": A Girl's Best Friend, aired initially as a Christmas special in 1981. Although the pilot fared well in the ratings, the BBC decided not to proceed with a series. After the 2005 return of the series, three spinoffs were made — Torchwood, The Sarah Jane Adventures and K9.
When the script called for him to recite coordinates to program the TARDIS, Tom Baker would sometimes rattle off a string of digits that was actually the telephone number to the Doctor Who production office; no one ever caught on.
"Dalek" and "TARDIS" became so familiar to British audiences that they were added to the Oxford English Dictionary.
Several versions of the theme tune were used over the years, with the most famous being used from 1963 to 1980 (albeit with a slight rearrangement and the addition of an echo chamber effect being added in 1966). A disco version of the tune became a hit in the UK in 1978, and in 1988, The Timelords (later to be famous as the art rock/techno act The KLF) had a #1 hit with "Doctorin' the Tardis", a song that mashed the theme song together with Gary Glitter's "Rock and Roll Part 2" and Sweet's "Blockbuster".
The version of the Doctor Who logo that was used from 1970 to 1973 during the Jon Pertwee era would later resurface as the logo for the 1996 revival film, after which it once again became the official logo for most Doctor Who-related merchandise. As of 2005, it is used as the official logo for the "classic series" with a brand new logo◊ used on all merchandise relating to the Russell T Davies era and a second new one◊ used on all merchandise relating to the Steven Moffat era.
Due to ill health, William Hartnell was unable to appear in the third episode of The Tenth Planet, which was also his penultimate episode. Ironically, the final episode of the serial has since been lost and consequently the last surviving episode from the Hartnell era doesn't even feature Hartnell.
TV editing was very difficult in the 1960s, and so (in common with most other British TV drama at the time) many early episodes of "Doctor Who" were recorded "as live". If the actors fluffed their lines, the others had to cover for him/her. There are several obvious instances of this in the series, such as in The Web Planet where actor William Hartnell forgot his lines, leading to co-star William Russell to prompt him by asking "What galaxy is that in then, Doctor?". In order to facilitate this style of recording, the actors were allowed a four-day rehearsal period (Monday-Thursday) followed by camera rehearsal on Friday day and the actual studio recording Friday evening. Saturdays were often spent on location recording inserts for future episodes, and the actors were given Sunday off before the process started again for the next episode on Monday morning. Although editing techniques improved over the years, it remained the case that studio scenes would usually be taped almost as live, using a multi-camera system, until the series ended in 1989.
Michael Jayston, a Shakespearean actor, played an evil Enemy Without of the Doctor known as the Valeyard who was created somewhere between Doctor's twelfth and final incarnations.
In the 1976 season, the Doctor started operating his TARDIS from the craft's secondary control room, an obviously older version of the main control room with wood paneling and a Victorian design motif. This set was abandoned when it was discovered that the paneling warped while in storage during the hiatus and the series had the Doctor begin using the regular control room again.
The music playing when the Fifth Doctor visits the Brig in Mawdryn Undead is a traditional English dance melody called "Lillibullero". It's sometimes attributed to Henry Purcell.
The music playing on the Major's gramophone in Carnival of Monsters is the 1925 hit "Has Anybody Seen My Gal?"
11th Doctor Matt Smith guest-starred on an episode of Billie Piper'snote Rose Tyler, in case you forgot show Secret Diary of a Call Girl as a shopkeep who ends up bedding Piper's character.
Troughton's pre-Who career involved a large batch of family television, including appearing in a Robin Hood series (interestingly, his grandson was Much in the 2006 TV version). Later he played Father Brennan in The Omen.
Tom Baker played Rasputin in the film Nicholas And Alexandra (1971). Perhaps the most recognisable Doctor voice, impressionist Jon Culshaw has often used the voice for telephone spoofs in Dead Ringers.
A scene in Remembrance of the Daleks involving Ace inspired the creation of the Crowning Moment Of Awesome section, which dropped the "Crowning" later on.
First live-action TV show on this site to get its very own gush page since it's so beloved.
Ascended Fanon: As a long-time fan himself, Steven Moffat incorporated his own fan theories into the show, such as the reason why the Doctor never reveals his name, because there is some Dark Secret behind it. This plot point literally became cliffhanger at the end of Series 6, where it's revealed that the reason the Silence want the Doctor dead is to prevent the Question from being answered.
Doctor: What Question?
Dorium: The Question. The oldest one in the universe, hidden in plain sight! Doctor Who?!
He also incorporated his theory that the word 'doctor' has come to mean 'healer' (or something similar) throughout the universe because of the Doctor going around introducing himself as 'Doctor' wherever he goes.
Cash Cow Franchise: The BBC has been prompt to capitalize on the show's new-found success since it returned. Two decades of Expanded Universe literature and audio have also helped.
Maureen O'Brien was 22 when playing the teenaged Vicki.
Dodo was a teenager but Jackie Lane was almost 25.
Zoe's age varies depending on what production member you ask, but she probably wasn't intended to be out of her teens, like Wendy Padbury was.
Turlough was supposed to be posing as a British schoolboy. Mark Strickson looked quite a bit older than his character, quite frankly.
Sophie Aldred was 24 when Ace was 16.
Karen Gillan, Arthur Darvill and Nina Toussaint-White played school-aged versions of Amy, Rory and a teenage-passing-for River in "Let's Kill Hitler" at ages 23, 29 and 25.
Jean and Phyllis in "The Curse of Fenric", who are supposed to be teenagers, although both actresses were in their early twenties at the time of filming.
Enforced Method Acting: According to Word of God, Alex Kingston (River Song), Karen Gillan (Amy), and Arthur Darvill (Rory) all knew certain things about their character that hadn't been revealed. These details had been intentionally withheld from Matt Smith. So when he doesn't know something, he really doesn't know.
The show's cancellation following the Sylvester McCoy era has been explicitly, if not exclusively, pinned on BBC executive Michael Grade's personal distaste for it (though he was no longer controller by the time of the actual cancellation).
Seventh producer Philip Hinchcliffe was moved on from the show following complaints about the levels of violence and horror during his tenure.
The sacking of sixth Doctor Colin Baker was at the behest of BBC management.
Executive Meddling is why Susan was the Doctor's granddaughter: it looked too odd otherwise.
Executive Meddling actually made Tegan have the '80s Hair, amusingly enough. Producer John Nathan-Turner somehow thought that fans might somehow mistake Janet Fieldingnote dressed in a purple pastel outfit for Adricnote ...who was a boy wearing bright yellow and dull greens in long shots. It's a miracle that Ms. Fielding didn't take the guy's head off.
Turlough had red hair to differentiate Mark Strickson (schoolboy outfit) with Peter Davison's Fifth Doctor (cricketing uniform).
Kamelion was originally going to be played by a series of humans, as he was a shape-changing robot. Instead turned into a real mechanical prop, which was then shelved when the only person on the planet (and we mean the real planet Earth) who knew how to operate the blasted thing died without telling anyone else how to work it.
A reference that Ace lost her virginity to Sabalom Glitz never made it past the censor.
Executive producer John Nathan-Turner demanded the Sixth Doctor's becoming "totally tasteless" in terms of fashion sense, rather than the Ninth Doctor-esque dark clothes and jacket Colin Baker wanted. And thus, the multicoloured suit was born.
Anthony Ainley wanted to play the Master as serious and understated, but the producers wanted a retread of Roger Delgado's over-the-top villain. It wasn't until "Survival" that Ainley was allowed to give the performance he wanted.
In "Planet of Evil", Sorenson was going to die, but the producer felt the death of a sympathetic character was inappropriate.
The ending to episode 11 of "The Trial of a Time Lord" was supposed to be a model shot of the Hyperion III flying towards the Black Hole of Tartarus. John Nathan-Turner thought that all episodes of the "Trial" season should end on a close-up on the Doctor's face however (even though episode 9 memorably avoided that), and had the episode re-edited to end on a shot of the Doctor looking vaguely annoyed at Lasky.
"The Ultimate Foe", also known as episodes 13 and 14 of "The Trial of a Time Lord" was to be a four-part story written together by Robert Holmes and script editor Eric Saward. Then it was turned into a two-part story when Pip and Jane wrote a pretty sweet story. Then, after Holmes passed away, Eric turned in a final script that kept the original plot; in this ending, the Doctor and Valeyard are left tumbling through the Matrix, fighting to the death. note (You know, similar to the ending of that one episode of the Original Star Trek where that guy fought himself between universes for all eternity. Something like that.) Producer John Nathan-Turner rightly felt this could give the BBC the excuse they needed to axe the program... so Saward resigned and refused permission for his script to be used. As such, the televised version of the final episode was written by Pip and Jane Baker in a matter of days, without being allowed to know anything about the originally intended version. People, it's nothing less than a miracle that this serial was even finished.
The first edit of "The Trial of a Time Lord Part 14" ran to some 38 minutes; Nathan-Turner managed to get permission to extend the running time by five minutes, but still had to make it up by cutting out large amounts of material featuring the Master and Glitz.
Executive Veto: Midge's somewhat unexplained death in Survival is because the original script had the Master inciting the other youths to tear him limb from limb for showing weakness, which was vetoed as too horrific even for Doctor Who.
The classic example is Bill Filer in The Claws of Axos. He even has his own fan-produced spinoff.
Peri Brown. Bryant's agent would only sign her if she got cast as the companion, and the casting agents were only looking for Americans. So she pretended to be American — John Nathan-Turner didn't know, Peter Davison didn't know, even Colin Baker only found out the truth six or eight months into shooting.
The newer series has improved significantly on this, if not totally averted it, however. Most American parts are finally being played by real Americans. However, several actors in "Daleks in Manhattan"/"Evolution of the Daleks" still come from the UK.
British father and son W. Morgan Sheppard and Mark Sheppard play old and young Canton Delaware in "The Impossible Astronaut"/"Day of the Moon".
Yee Jee Tso, who played Chang Lee, is actually Canadian.
Fandom Nod: In "Blink", policeman Billy Shipton tells Sally Sparrow the TARDIS can't be a real police box because "the windows are too big" (amongst other things). It's been confirmed by episode writer Steven Moffat that this was a reference to complaints made by fans on the popular Outpost Gallifrey discussion forums in 2004. (Likewise "Time Crash" and "Love & Monsters" both make oblique reference to Fandom.)
The Storm / The Oncoming Storm, the moniker used by the Daleks in the Time War.
The Valeyard, based on a theory that this is said character's re-introduction to the Whoniverse: both are "dark incarnations of The Doctor; he really would be a Doctor who abandoned "the name of The Doctor" both metaphorically and physically; and both, to quote, "had no choice" in their evil actions.
Pat Gorman, who made a career out of performing stunts and playing monsters and bit parts, actually appears in more episodes than Peter Davison. Some other frequently recurring faces in the Whoniverse are actors Michael Sheard, Bernard Horsfall, Philip Madoc, and John Scott-Martin.
The new series also has a batch of recurring monster-suit actors, with Paul Kasey and Ruari Mears being the two most prominent. Paul Kasey is actually the only actor to have appeared in every series since the show's return in 2005, with his first involvement being as the lead Auton in Rose. Both have also appeared on The Sarah Jane Adventures, with Kasey additionally making recurring appearances on Torchwood.
Ruari Mears appears unmasked as one of Miss Foster's guards in Partners in Time. The other is played by Claudio Laurini, another recurring monster actor/extra.
Sharp-eyed viewers may also recognize Christine Adams (Cathica) as Simone, Emerson Cod's love interest in Pushing Daisies. Tamsin Grieg (Fran from Black Books) has a small part as the saleswoman who convinces Adam to get a hole in his head.
Pegg's Spaced co-star/co-writer Jessica Hynes plays Joan Redfern in Human Nature.
Viewers may have a hard time understanding why the Marquis de Carabas is fighting for his life on Satellite 5, and being a total douchebag about it.
In Terror of the Vervoids Professor Lasky is Cathy Gale. To Australian viewers of a certain age, Commodore Travers is immediately recognisable as the star of the medical drama G.P.
David Tennant himself is one of these, being such an unrepentant fan of the show that he lent his voice to several Expanded Universe audio productions and narrated a special documentary aired before the first episode of the 2005 revival, prior to finally landing his dream job.
The voice of the Great Intelligence in "The Snowmen" is Ian McKellen.
I Knew It: A few fans successfully guessed the revelation regarding Clara in "The Name of the Doctor": that the modern London Clara is the original and somehow ends up splintered across time to save the Doctor's life countless times.
Arthur Darvill had several guesses as to River Song's true identity before it was revealed on the show, and would sometimes bug Alex Kingston with them on set (she being the only person other than Moffat who knew). Eventually he guessed right, and she just said "Hello, Dad."
Rassilon turning out to be evil in "The End of Time" was this for many fans. "The Five Doctors" and much Doctor Who Expanded Universe material had already depicted him as fairly shady.
After he first appeared in "The Name of the Doctor", fans speculated that the War Doctor was a previously unknown incarnation of the Doctor from between his eighth and ninth incarnations. The minisode "The Night of the Doctor" proved this to be true.
Keep Circulating the Tapes: The 1993 charity special Dimensions in Time, a crossover with EastEnders, was created on the condition that it'd never be rerun or released on home video. You can find it on YouTube, however.
Meaningful Release Date: "The End of Time", "The Big Bang", and "The Impossible Astronaut" are set on their airdates (accounting for British time zones).
The first episode of the Mc Coy-era Silver Nemesis aired the day before it was set.
Name's the Same: Strax the Sontaran medic shares his name with a controversial Florida medical facility. This could be coincidence... or Moffat could have picked up the name while visiting the US. He does have an affinity for Space Florida, after all…
In World War Z, Peter Capaldi played a "W.H.O. Doctor". According to rumors, this was done deliberately as a joke on the part of casting.
The King Kong Show had a bald, villainous scientist named "Dr. Who". When the same character showed up in the film King Kong Escapes, they gave him grey hair and a cape, there were too many similarities.
Americans had to wait until 1972 before finally seeing an episode on their screens. Nearly happened again in 2005 when US broadcasters initially refused to buy the new series, reportedly because it was "too British".
From about 2006 to 2010 it was commonplace for online content produced related to the series to not be viewable outside the UK (behind the scenes videos, prequels, games etc). This has improved in the last couple of years, but there is still extensive content that cannot be viewed outside the UK (at least until someone posts it to YouTube...). Although some original content eventually makes its way onto DVDs that get released in North America, there have been some notable exceptions, such as the "TARDI Sodes", a series of prequels released online in the UK only and never included on DVD, and Captain Jack's Monster Files, a web series featuring John Barrowman that remains web-only in the UK.
Initially applied to a series of computer games produced for online distribution beginning in 2010. Eventually were made available via a retailer with North American release rights, except for the Mac version, even though it was available for Mac in the UK.
In a minor reversal, only viewers in North America and Australia viewed a unique pre-credits sequence narrated by Karen Gillan that was added to non-UK broadcasts of Season 6 in order to introduce new viewers to the show. This opening never made it onto the DVD releases in the UK or anywhere else.
Heavily subverted with "The Day of The Doctor". Normally, there's several hours between the airing in the UK and the airing in the US, allowing fans to find and download the episode. For Do TD, the episode was shown at the exact same time in 94 countries, awarding a Guinness record for biggest global simulcast.
BBC Worldwide's Asia arm has never been good with the specials. However, most egregiously, The Time of The Doctor has been skipped over, and this special is important as it showcases the regeneration of Matt Smith to Peter Capaldi, and regenerations are extremely important events to Whovians. Many have wrote to the BBC, who claims that they have noted the interest of Asian viewers in the episode, but have announced that it will not be aired in the near future, and mentions nothing about it airing in the distant future. And oh, the pre-2005 episodes have never been aired on BBC Asia's feeds, either.
The Other Darrin: Generally averted in favor of The Nth Doctor. It's played straight, however, with the recasting of the late William Hartnell as the First Doctor in The Five Doctors. The recurring villain Davros has also been played by four different actors on TV - the heavy make-up helps to disguise it, but their voices are definitely different.
Done for a grand total of 3 seconds during the Sixth Doctor's regeneration process, as Colin Baker didn't return to portray the Doctor for a fraction of an episode. The Sixth Doctor's Dick Sargent to Colin Baker's Dick York was Sylvester McCoy, who simply wore a curly blond wig while sparkly special effects covered his face. It didn't work. Leave it to the producers of the "Time and the Rani" DVDs to sneak an Easter Egg in that seeks to make the regeneration look better by carefully rotoscoping in Colin's face, which is, soothingly, much better.
Colin Baker jokingly insists that since he never actually regenerated, he's still the Doctor and all the later ones are mere pretenders to the part.
Playing Against Type: Then-known for his comedic talents and funny voices, Jon Pertwee subverted his own screen persona with the no-nonsense performance of the Third Doctor.
Colin Baker had been a fan of the franchise since the first episode was aired and leapt at the chance to even be in the story, much less portray the Doctor himself. He's also the president of the Doctor Who Appreciation Society.
Nicholas Briggs started out creating and starring in fan audios (Doctor Who Audio Visuals) using half a dozen pseudonyms. He managed to befriend all of the cast and crew of Doctor Who, created documentaries, convinced many of the Doctors and companions to star in The Stranger and The Airzone Solution (both written by him), and eventually became the Show Runner of Big Finish Doctor Who. He promptly re-wrote many of his Doctor Who Audio Visuals into official episodes. Oh, and he now voices the Daleks and the Cybermen in the TV show.
David Tennant. Not only did he start acting just to become the Doctor, there was a special that landed him with his favorite Doctor, Peter Davison. The following year, Tennant met Peter's daughter Georgia, fell in love and proposed, later having a child together, Olivia. Not only is Tennant clearly the ultimate Promoted Fanboy, but Olivia is the only person who can claim both her father and grandfather were the Doctor.
The cancellation of the classic series in 1989 was originally described as a "hiatus" by the BBC. And it was, of a sort. It just lasted considerably longer than the earlier one: at least seven years (until the 1996 TV movie) and up to sixteen years (until the series resumed on a regular basis with "Rose" in 2005).
Sure, Why Not?: In the Comic Relief special "The Curse of Fatal Death", the Doctor regenerates into a woman. In The End of Time, the Eleventh Doctor feels his face and hair and freaks out, thinking he's regenerated into a woman. In The Doctor's Wife, the Doctor mentions that the Corsair has had both male and female incarnations. In The Night of the Doctor, the Sisterhood of Karn gives the Doctor the chance to control his next regeneration, part of the choices being a woman.
"The Invasion of Time". Firstly the original writer gave the production team a set of scripts that would have been impossible to realize on a film budget, resulting in the producer and script editor having to come up with a totally new storyline in just a few days. Then the UK's economy imploded due to the Winter of Discontent, rendering the British Pound nearly worthless and leaving No Budget for the serial. On top of all that, virtually every department of the BBC went on strike at the same time, resulting in a hasty studio session filmed with sets left over from "The Deadly Assassin," followed by location filming at anywhere which would let them shoot, just so that they could get everything in the can. Not to mention the producers didn't believe that the actress playing Leela really wanted to leave, so they delayed writing in her exit and had to add a hastily written romance with Andred.
"Warriors of the Deep". The production schedule lost two weeks due to an early Parliamentary election, which explains many of the serial's shortcomings. The other shortcomings stem from the set designer, who wanted everything brightly lit to show off his work, and the director, who wanted everything dark and moody for atmosphere, preceding a similar situation on Aliens by two years.
After the location filming for "The Greatest Show in the Galaxy" had been completed, the studio sessions were cancelled because of asbestos contamination. At first it was thought that the serial would have to be abandoned, but eventually it was found possible to erect a tent in the car park at Elstree Studios and film there.
Viral Marketing: There have been, at various times, an actual Cybus Industries website, a conspiracy site based on the one from the first revival episode, and another telling you to vote for Mr. Saxon.
The Canadian animation studio Nelvana at one point proposed a Doctor Who animated series, which never got beyond the concept art stage. It would apparently have featured a Doctor who dressed like Tom Baker's version but bore a heavy facial resemblance to Christopher Lloyd.
Similarly, when RTD was writing "The Waters of Mars," he wrote the character of Adelaide Brooke with Helen Mirren in mind.
The Ood were created for "The Impossible Planet" / "The Satan Pit" because the prosthetics were cheap — originally the Slitheen would've filled the role. Later in "The Doctor's Wife", an Ood again appeared because there was no budget for the new original alien Neil Gaiman had designed.
Adric's character was originally conceived as "an Artful DodgerIN SPACE!," though largely in terms of his relationship with the Doctor. While wisps of this concept crop up in Adric's abilities once in a blue moon, the student-mentor dynamic more or less runs headlong into a brick wall after the Fourth Doctor regenerates.
Many, many unmade and/or unfilmed serials and projects for the serial are documented on this Wikipedia article.
"The Mark of the Rani" and "Paradise Towers" both had different soundtracks during production. However, the composer on the former story suffered Author Existence Failure before he could finish the soundtrack, while the latter story's composer got canned after John Nathan-Turner decided the soundtrack was too dull and lacking in energy. The DVD releases of both stories include the alternate soundtracks.
Simon Pegg was originally slated to play Rose's father, Pete Tyler. However, Pegg was unavailable during the filming of "Father's Day", so his role was transferred to that of the Editor.
Originally, Survival's Cheetah People were supposed to be a lot more human-looking, with their possession by the cat-spirits of the Cheetah World represented by false eyes, teeth and some skin-colouring to suggest cheetah spots. Then, someone decided it'd be a good idea to make them actual Cheetah People. The writer, Rona Munro, was less than impressed by the result, describing the end effect as 'puss-in-boots'.
Russell Tovey, the actor who portrayed Alonso in "Voyage of the Damned" and "The End of Time", was actually a strong candidate to play the Eleventh Doctor, and would have likely gotten the role had Matt Smith not auditioned for it.
At one point RTD was planning on talking to his opposite numbers in the USA who were behind the Star Trek franchise about doing some type of crossover or charity special, but the cancellation of Star Trek: Enterprise put an end to it, although the legal and logistical concerns made it a long shot to begin with. There is, however, now a comic book miniseries that crosses over the franchises.
Disney considered buying Doctor Who in the late 80s and early 90s, and was even considering opening up a "walk-through" TARDIS in Disneyland if they did.
Wilfred Mott was originally meant to be just a one-shot character. He was only written as Donna's grandfather after the man who was going to play Donna's father vacated the role due to dying.
The appearance of The Beatles on the Space-Time Visualiser was originally scripted to be the band playing a concert at some point in the future as old men. The Beatles themselves were reportedly interested, but this was nixed by their management and a promo of "Ticket to Ride" filmed for Top of the Pops was substituted instead. Given what would happen to John Lennon well before he reached old age, this also had the unintended effect of nixing a potential "Funny Aneurysm" Moment as well.
John Nathan-Turner was keen to reintroduce a familiar companion to the regular cast to ease the transition from Tom Baker to Peter Davison after the former's seven year tenure in the lead role, and approached both Elisabeth Sladen and Louise Jameson to ask if they would like to reprise their parts as Sarah Jane Smith and Leela respectively. Neither were interested in going back to the programme, so Tegan was created instead.
The original last line of "Revelation of the Daleks"? "I'm taking you to Blackpool!" Because the next story "The Nightmare Fair" took place in Blackpool. The series was put on an 18-month "rest" after nearly being cancelled, so the edit was made to cover up the last word.
Once Bonnie Langford decided she was leaving, initially the new companion was going to be Ray from "Delta and the Bannermen"; the production team later went with Ace, but we could have had a 1950s Welsh tomboy mechanic travelling with the Doctor instead...
Funnily enough, Sophie Aldred, who initially auditioned for the part of Ray (she is fully qualified to drive motorbikes), was asked to reapply for the part of Ace.
"The Happiness Patrol" was originally planned to be filmed in black-and-white to compliment its Film Noir-ish atmosphere.
Kandyman was originally a portly, bald man with black teeth and wearing a white lab coat. Costume designer Dorka Nieradzik turned him into the Bertie Bassett-like robot seen.
"Lungbarrow" very nearly made it to air, but was nixed by the producers and ended up as a New Adventure title instead. Focusing on the Doctor reunited with his estranged family, the story was less about Sylvester McCoy and more a re-imaging of Gallifrey in keeping with his darker Doctor; less Crystal Spires and Togas, and more "The Addams Familyon acid."
Interestingly, the original concept of the 1996 movie actually focused on the Doctor learning that he was half-human, and that the Master was his long lost half-brother. However, these concepts get the occasional Discontinuity Nod in canon nowadays. Paul McGann's screen test shows some snippets of the original script.
A deleted subplot from "The Long Game" was to have revealed that Adam's father suffers from arthritis, and the first thing Adam looked up before he looked up "fabulous wealth-making future technology" was potential cures. It was presumably cut because it would have made Adam more sympathetic than he was intended to be.
A few sources claim that House, the villain of "The Doctor's Wife", was originally to be the Great Intelligence.