The Tenth Planet is the second serial of the fourth season of the British science fiction television series Doctor Who. Written by Kit Pedler and Gerry Davis and directed by Derek Martinus, it was broadcast on BBC1 in four weekly parts from 8 to 26 October 1966. In the serial, the Doctor (William Hartnell) and his travelling companions, Polly (Anneke Wills) and Ben Jackson (Michael Craze), arrive at a space tracking station on the South Pole in 1986, where they encounter the Cybermen, whose planet, Mondas, is absorbing energy from Earth and will soon destroy it.
The serial marked Hartnell's final regular appearance as the Doctor; at the end of the fourth episode, the character "regenerates" into a younger man, portrayed by Patrick Troughton. The Tenth Planet was also the first appearance of the Cybermen, a race of malevolent cyborgs conceived by Pedler due to his fear of humans replacing their organs and limbs mechanically through "spare-part surgery"; a reflection of their era, they subsequently became one of the programme's most iconic recurring villains. The serial was the first in Doctor Whos fourth production block, with early filming at Ealing Studios from August 1966 and primary recording at Riverside Studios from September to October.
The Tenth Planet received an average of 6.75 million viewers across the four episodes, halting the programme's declining viewership. Reviewers enjoyed the direction, performances, and the introduction of the Cybermen, though some found the story confusing and nonsensical. The fourth episode was wiped by the BBC and remains missing; the only extant material includes the regeneration scene, though an animated reconstruction was released in 2013. The story was novelised by Davis, and the serial was released on VHS, DVD, and as an audiobook, while sounds and music have been released on CD. The introduction of regeneration has been credited with establishing Doctor Whos ongoing longevity.
Plot The TARDIS lands at the South Pole in 1986. The Doctor and his travelling companions, Ben and Polly, are taken to the Snowcap Base space tracking station. Commanded by General Cutler, the base is monitoring a crewed space probe being drawn off-course by an unknown force, and they discover a new, unknown planet approaching Earth. Recognising identical landmasses to those of Earth, the Doctor reveals it is Mondas, the Earth's long-lost twin planet.
A mysterious spaceship lands in the snow and three robotic creatures take control of Snowcap Base. They are Cybermen, former human beings who have replaced their bodies with mechanical parts, and no longer have the "weakness" of emotions. The base staff watch helplessly as the space probe is destroyed by the gravitational pull of Mondas. The Cybermen explain that Mondas is absorbing energy from Earth and will soon destroy it. They propose to take humans back to Mondas and turn them into Cybermen.
The humans mount a resistance and kill the Cybermen with their own cyberweapons. Cutler plans to destroy Mondas using a Z-bomb nuclear missile; he is opposed by his chief scientist, Dr. Barclay, and Space Command HQ in Geneva, as the radiation from the exploding planet would cause immense loss of life on Earth. The Doctor, unwell, passes out. Cutler detains the Doctor and Ben in a cabin. Ben escapes, sabotages the rocket, and the Z-bomb launch fails.
A new squadron of Cybermen arrive, kill Cutler, take control of the base, and order the Z-bomb to be disarmed. Cybermen invade Earth and take over Geneva Space Command. The Doctor realises that Mondas is absorbing too much energy and will be destroyed, and that the Cybermen plan to destroy the Earth with the international arsenal of Z-bombs to save Mondas. The Doctor and Polly are imprisoned on the Cybermen's spaceship. Ben and the base crewmembers overpower the Cybermen and regain control of the base. As more Cybermen enter the base, Mondas explodes. Disconnected from their power source on Mondas, all the invading Cybermen on Earth collapse and die, ending the invasion.
Ben frees the Doctor and Polly. The Doctor, ill, returns to the TARDIS. Ben and Polly follow, and find the Doctor has collapsed unconscious on the floor. As the sound of the TARDIS engines is heard, the Doctor is covered in a luminous light and transforms into a younger man.
Production Conception and writing Kit Pedler (an academic at the University of London) was invited to submit story ideas for Doctor Who following his advisory role on the serial The War Machines (1966). He was inspired by two scientific elements: a space capsule suddenly losing energy, topical to the ongoing Space Race; and "star monks" coming from Earth's "twin planet" on a religious quest. Davis found the latter too similar to the Monk from The Time Meddler (1965) and suggested Pedler focus on his fears as a scientist instead of science-fiction concepts. Pedler's primary concern was the idea of machines replacing human organs and limbs; he discussed the idea of "spare part" surgery with his wife, and was intrigued by the concept of a cybernetic man—"Cybermen"—and whether they would maintain their souls. His initial concepts included their arms being placed lower on their body than humans. The programme's script editor, Gerry Davis, formally commissioned Pedler's serial, Doctor Who and the Tenth Planet, on 17 May, with scripts due by 6 June.
Pedler delivered the first three draft scripts on 18 and 25 May and 3 June, and the fourth in early June, before being admitted to hospital with ulcerative colitis. Davis completed rewrites on the scripts for the third and fourth episodes, for which he was given staff contribution clearance on 29 June; he was paid half of the scripting fee and copyright on the concept of the Cybermen, to which Pedler agreed on 13 July. Davis worked on the scripts on the evenings and weekends, as he was busy working on both the preceding story, The Smugglers, and the following one, The Power of the Daleks. Pedler and Davis's names were misspelled as "Kitt Pedler" and "Gerry Davies" in the first and third episodes, respectively. Davis and producer Innes Lloyd felt The Tenth Planet was their first original story for the programme, having adopted the preceding serials from their predecessors; they were happy with the serial and considered it a blueprint for later stories. It was Doctor Whos first story set in the near future, and its first "base-under-siege" story. Davis and Pedler hoped the Cybermen would become as successful as the Daleks; their voices were scripted as "flat but not Dalekish, hard in tone". Anneke Wills and Michael Craze (who portrayed Polly and Ben, respectively) were excited to have a story written by a scientist.
Derek Martinus was assigned as the serial's director, following his work on the third-season serial Galaxy 4 (1965). Sonia Markham, who had supervised makeup for Doctor Who since the first-season serial The Reign of Terror (1964), was replaced by Gillian James on The Tenth Planet. The Tenth Planet was Peter Kindred's first work as a designer on the programme, and he had about three weeks to prepare before filming. He and Martinus approached the serial as scientific and realistic instead of science fiction. Pedler's scripts indicated that the Polar Base's tracking room should be based on Cape Kennedy and the space capsules resemble the Gemini capsules, and the polar setting was inspired by one of his favourite films, The Thing from Another World (1951). Brian Hodgson created twelve sounds for the serial, including the Cybermen guns and the malfunctioning TARDIS, while stock music was used in place of an incidental score. An animated graphics sequence for the opening and closing credits was designed by Bernard Lodge on 16 mm film.
Costume designer Daphne Dare was replaced by Sandra Reid, who discussed cybernetics with Pedler and Martinus before crafting the Cybermen with Kindred. A silk jersey was used for the face masks, while a full-length wool jersey bodystocking was used for the "skin", with a transparent polythene suit atop it. The costumes were heavy, held together with nuts and bolts holding together plastic piping and metal epaulettes. The metallic headpieces were created by Shawcraft Models, adapted from a truck headlamp; the bulb exploded in the first test shot, abandoning the idea of illuminating the halogen lamp. The actors wore Wellington boots, and James added silver-blue makeup to their hands as Reid forgot to make gloves, for which she was regretful; Wills felt the makeup gave the Cybermen a suitably human quality. Seven Cyberman costumes were made, of which three were fully practical. The Doctor's costume matched his outfit in his first serial: scarf, cloak, and Astrakhan hat.
Casting and characters
Lead actor William Hartnell had felt unsettled on Doctor Who since the original cast and production team had departed in 1965. He found the programme had become increasingly "evil" and suggested more whimsical stories for its young audience, while the newer producers had found him difficult to work with; former producers had considered replacing him during The Celestial Toymaker (1966) before his contract was renewed. Lloyd, whom Hartnell respected, suggested that the actor depart the role and be replaced; Shaun Sutton, the head of drama at BBC Television, felt a new lead actor may reverse the programme's decreasing viewership. Davis considered that the Doctor could die and be reborn, and Lloyd suggested the character could occasionally rejuvenate himself into a younger man. This idea was incorporated into The Tenth Planet, for which Hartnell was contracted in mid-June 1966, following the expiration of his regular contract at the end of The Smugglers. For the transformation sequence, Davis had been inspired by The Strange Case of Dr Jekyll and Mr Hyde (1886).
Hartnell's departure was formally announced on 5 August; Hartnell said he felt "three years in one part is a good innings and it is time for a change". Several actors were considered for Hartnell's replacement, including Michael Hordern, Ron Moody, Tommy Steele, and Patrick Wymark. It was ultimately offered to Patrick Troughton in late June, and he was contracted for 22 episodes on 2 August and for The Tenth Planet on 16 September. Hartnell approved of his casting, according to Lloyd, and Wills recalled Hartnell was honoured to be replaced by an actor of Troughton's calibre. Troughton's role was formally announced on 1 September. Before recording the fourth episode, the production team realised Troughton had not been assigned a dressing room; he was given the one assigned to guest star Callen Angelo, who instead was moved to share with Steve Plytas.
Martinus began casting guest roles in August 1966, opting for some non-British actors to reflect the multinational organisation. Robert Beatty, whom Martinus had directed in a production of The Man Who Played God (1961), was cast on 3 August as General Cutler, described by Martinus as similar to General MacArthur. Hartnell had guest-starred alongside Beatty on Dial 999 (1958–1959) and they enjoyed working together again. Australian actor Alan White portrayed Schultz (originally written as a German), while Bermudan actor Earl Cameron was cast as Glyn Williams (written as a Welshman), reportedly becoming the first black actor to portray an astronaut on screen and the second black actor in a speaking role on Doctor Who (after Elroy Josephs in The Smugglers). Wills recalled Hartnell's prejudice was exposed when working with Cameron, which ashamed her and Craze; Cameron said he was not aware of it, calling it "his problem, not mine". Beatty and Cameron were billed as the serial's top guest stars.