The Daleks "The Dead Planet" (partially found unaired original episode of Doctor Who serial; 1963)
Barbara is approached by a Dalek. The original recording of this scene was included in the opening reprise of "The Survivors".
Status: Partially Found
"The Dead Planet" is the title of the first episode from the Doctor Who serial The Daleks. Originally airing on 21st December 1963, it marked the first appearance of the Daleks, relentless cyborg killing machines that became the show's most iconic villains. While the full serial was narrowly - and famously - saved from being wiped by the BBC in 1978, what is lesser-known is that there was an earlier version of The Dead Planet, which never aired on television.
"The Dead Planet" was the second serial (multi-episode storyline) from the BBC science-fiction series, featuring the First Doctor (William Hartnell) his granddaughter Susan Foreman, and fellow companions Ian Chesterton and Barbara Wright. In this opening episode, the quartet are on a visit to the planet Skaro, a radioactive wasteland following the culmination of the Thousand Year War between the Kaleds and the Thals.
After exploring the ruins of a jungle, they run across an oddly intact settlement named Dalek City. Intrigued, the Doctor decided to investigate further - this over the objections of Ian and Barbara, who have become convinced that unknown but potentially dangerous entities are watching them. To persuade the duo, the Doctor shamelessly lies that the TARDIS' crucial fluid link is out of mercury, a metallic element which can only be obtained in the City. Shortly after arriving, the travellers become separated from one another, and Barbara ends up sealed within a confusing, claustrophobic maze of featureless corridors. Just as she reaches the end of one hallway - having seemingly exhausted every possible means of escape - something slowly approaches her and extends a menacing metal arm, as the episode fades out on her screams.
"The Dead Planet" proved a solid ratings success, drawing 6.9 million viewers. As the seven-part serial continued to air, word of mouth regarding the titular Daleks attracted millions more, topping out at 10.4 million for both "The Ordeal" and "The Rescue". The serial instantly made the quasi-mechanical beasties and their monomaniacal determination to "Exterminate!" all organic life an iconic element of Doctor Who - and thus guaranteed the show's survival, which was initially uncertain thanks to the lukewarm reception of the previous serial, An Unearthly Child. The Dead Planet's ending is also considered one of Doctor Who's greatest cliffhangers.
Unlike over 97 episodes of the series, The Daleks was not victimised by the BBC's tape-wiping practices, which saw recordings of older works be erased so that the expensive master tapes could be reused as a means of saving costs. However, this was only due to a last-minute intervention to save these episodes among others in 1978.
Filming for "The Dead Planet" began on 15th November 1963, the serial (originally known as "The Mutants") having only been approved by a reluctant Sydney Newman as others were still in earlier stages of pre-production. Due to budgetary concerns and the need to conform to strict broadcast deadlines, filming the first Doctor Who serials was generally a difficult task. Every scene per episode needed to be filmed sequentially, and essentially be shot "as live"; there was no routine editing process, and this often resulted in major quality issues not being detected until late in production if at all. These restrictions were particularly onerous on an effects-heavy sci-fi series, which had so far suffered numerous small technical issues, including the TARDIS' doors failing to properly function.
Nevertheless, filming on "The Dead Planet" seemed to have gone off smoothly, and optimism regardling the Daleks began to grow among the cast and production team. Upon reviewing the final product, however, it was clear disaster had struck. During filming, director Christopher Barry had communicated with production assistant Norman Stewart over headset microphones - a relatively standard process, except that in this case the audio from Stewart's headset had proved loud enough to be captured in turn by the studio mics.
Primitive television editing of the time could not overcome this challenge, and thanks to the lack of any mechanism for regularly reviewing rough footage, it had not been caught in time to reshoot. The episode was clearly about to fail the BBC's strict quality assurance tests, so the decision was taken by BBC's Head of Drama Serials, Donald Wilson, to re-do it entirely.  This was not an uncommon occurrence at the time, but not ideal; aside from being a bit hard on the production team's morale, it also delayed filming of the later episodes by another full week, with the reshoot set to be filmed on 6th December.
However, there were some consolations: the production team had not been entirely keen on the first miniature model of Dalek City, which lead designer Raymond Cusick felt was a touch too miniaturized and thus lacking detail. The delay allowed for this to be fixed to everyone's satisfaction.  Carole Ann Ford (Susan) also wore a different costume for the reshoot. It is possible other notable changes were made, given that previous serial An Unearthly Child had been heavily modified during its required reshoots, including such basic elements as the Doctor's outfit and personality.  
The famous cliffhanger ending is believed to be the only element of the original version to make it to air, as the reprise of the original scene used at the beginning of the next episode is identical to that in the reshot episode. No other part of the original is recorded as having been used, likely because of the audio issue.
Whereas the unaired "pilot" of An Unearthly Child surprisingly survived, "The Dead Planet"'s original recording is missing, and presumed wiped. It is unclear exactly when this happened, though it was likely discarded not long after being declared unfit for broadcast. This makes it the first known piece of Doctor Who lost media. A similar fate befell Part 4 of the First Doctor serial Planet of Giants, titled "The Urge to Live", with the serial reedited into three parts.
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- Doctor Who Episode by Episode: Volume 1 William Hartnell summarising The Dead Planet's narrative and its filming. Retrieved 28th May '23
- A Cup of Joe summarising The Daleks. Retrieved 28th May '23
- Blogtor Who summarising The Dead Planet and its cliffhanger ending. Retrieved 28th May '23
- Doctor Who World summarising the Thousand Year War which in narrative occurred significantly before The Daleks. Retrieved 28th May '23
- Shannon Sullivan providing a detailed account of filming for The Daleks, including the technical issues that plagued the first The Dead Planet recording. Retrieved 28th May '23
- Shannon Sullivan detailing the troubled production for An Unearthly Child. Retrieved 28th May '23
- Wiped! Doctor Who's Missing Episodes detailing how The Daleks serial almost became a casualty of the BBC's tape-wiping practices. Retrieved 28th May '23
- University of Warwick detailing the extensive number of lost episodes of Doctor Who. Retrieved 28th May '23
- The Sundae detailing the BBC's tape-wiping practices. Retrieved 28th May '23
- Doctor Who: The Complete History summarising filming for An Unearthly Child and The Daleks, detailing the technical issues that forced reshoots of both. Retrieved 28th May '23
- Lovarzi summarising the original version of The Dead Planet, and noting it is the first missing episode of Doctor Who. Retrieved 28th May '23
- Paul Ferry's Universal Omnibus comparing the pilot and broadcast versions of An Unearthly Child. Retrieved 28th May '23