The Sixth Doctor (1984-1986)
Season Twenty-One 
(1984) Season Twenty-One (1984): Change, My Dear
Season Twenty-Two (1985) Season Twenty-Two (1985): Instabilities
First appearance of the Rani.
Season Twenty-Three 
(1986) Season Twenty-Three (1986): On Trial
First appearances of Mel, the Valeyard, the Inquisitor and Sabalom Glitz.

Season Twenty-One (1984): Change, My Dear

The Doctor
The Sixth Doctor

Colin Baker (bio) made his first appearance as the Doctor in The Caves Of Androzani (March 1984) and his last in The Power Of The Doctor (October 2022).

The Story
The Twin 
Dilemma
The Twin Dilemma by Anthony Steven, directed by Peter Moffatt
The Doctor experiences regenerative instability, prompting him to live as a hermit amidst the desolation of Titan 3. There he rescues Lieutenant Hugo Lang, the lone survivor of a pursuit squadron destroyed by the immense power of the tyrannical Mestor. The Doctor learns that Lang was trying to rescue twin mathematical geniuses named Romulus and Remus Sylvest, and he recognises their kidnapper as his old friend, the Time Lord Azmael, whom he thought retired to the planet Joconda. The Doctor must discover the link between Mestor and Azmael, and the terrible purpose Mestor intends for the Sylvest twins.

Making History

When the Sixth Doctor embarked on his first adventure in the 1984 finale, it was just the second time in Doctor Who's history that a change of lead actor had occurred mid-season. The production office hoped that this approach would provide audiences with a chance to acclimate to the new TARDIS team prior to the long break before the start of Season Twenty-Two.

Season Twenty-Two (1985): Instabilities

Companions and Recurring Characters

The Rani was a ruthless Time Lord scientist who turned renegade in order to pursue her emoral experiments.

Kate O'Mara (bio) made her first appearance as the Rani in The Mark Of The Rani (February 1985) and her last in Dimensions In Time (November 1993).

The Rani

The Stories
Attack Of The 
Cybermen
Attack Of The Cybermen by Paula Moore, directed by Matthew Robinson
As Halley's Comet approaches the solar system in 1985, a strange force causes the TARDIS to malfunction. The Doctor detects a mysterious signal emanating from Earth, little realising that it's being transmitted by the mercenary Lytton, who is posing as the boss of a criminal gang. Meanwhile, Lytton has taken his cohorts into the London sewers, where they find the Cybermen waiting for them. And, on the planet Telos, the slave workers Bates and Stratton try to rebel against their Cyberman masters. In order to understand the connection between these events, it will fall to the Doctor to uncover Lytton's true loyalties.
Vengeance On 
Varos
Vengeance On Varos by Philip Martin, directed by Ron Jones
The TARDIS runs out of vital Zeiton-7 ore, so the Doctor makes an emergency landing on the planet Varos, which is rich in the mineral. Varos is a former penal colony, and its residents now derive pleasure purely from televised tortures. The Governor of Varos is struggling to negotiate a price for Zeiton-7 with Sil, the scheming representative of the Galatron Mining Corporation. To placate his unhappy people, the Governor orders the live execution of the rebel Jondar. When the Doctor and Peri intervene, they are forced to navigate the Punishment Dome, where they may become the latest victims of Varos' video nasties.
The Mark Of 
The Rani
The Mark Of The Rani by Pip and Jane Baker, directed by Sarah Hellings
The TARDIS arrives near the village of Killingworth at the time of the Luddite uprisings. The local mine owner, Lord Ravensworth, alerts the Doctor and Peri to a rash of violence which has recently erupted, threatening the work of famed engineer George Stephenson. The Doctor follows a series of clues to a bath house, where a renegade Time Lord called the Rani lurks in disguise. She has been sending the miners into a rage by harvesting brain chemicals for her amoral experiments. But the Master is also present, scheming to harness Stephenson's genius for his own use, and he and the Rani soon agree to join forces.
The Two 
Doctors
The Two Doctors by Robert Holmes, directed by Peter Moffatt
The Time Lords send the Second Doctor and Jamie to Space Station Camera, to put an end to dangerous temporal experiments. The Doctor appeals to his old friend, Dastari, but is betrayed: Dastari has genetically augmented a savage Androgum named Chessene, who has forged an alliance with the Sontarans. The captive Doctor is taken to Seville, where Dastari plans an operation to isolate the genetic code which permits time travel. Suddenly gripped by a memory of being executed in his second incarnation, the Sixth Doctor rescues Jamie and travels with Peri to Seville -- where both his past and his future are at stake.
Timelash
Timelash by Glen McCoy, directed by Pennant Roberts
The TARDIS lands on the planet Karfel, which is under the sway of the mysterious Borad. The Borad wields the power of a time tunnel called the Timelash, through which foes are banished, never to return. When the Borad kills the nominal ruler, Renis, and installs the scheming Tekker in his place, Renis' daughter Vena steals a vital amulet and throws herself into the Timelash. With Peri held prisoner, the Doctor agrees to follow Vena's trail, and he finds her in the care of a young writer named Herbert in nineteenth-century England. The Doctor convinces Vena to return to Karfel... but neither Tekker nor the Borad is to be trusted.
Revelation Of 
The Daleks
Revelation Of The Daleks by Eric Saward, directed by Graeme Harper
On Necros, Davros is posing as the Great Healer of Tranquil Repose, where dying patients sleep in suspended animation. He is allied with Kara, whose company produces a food concentrate which has eliminated famine in the galaxy. But Davros has become extortionate in his demands, prompting Kara to send the disgraced knight Orcini to assassinate him. Meanwhile, the Doctor and Peri arrive on Necros to attend the funeral of an old friend, Arthur Stengos. Also present is Stengos' daughter, Natasha, who discovers that her father has become a victim of Davros' experiments to create a new race of Daleks...

Making History

Season Twenty-Two saw a mix of old and new for Doctor Who, as the show returned to Saturday teatimes, but was now formatted as forty-five-minute episodes. Despite this, things did not fare well for the programme; ratings were down and there were renewed calls that Doctor Who was becoming too violent. Combined with financial issues within the BBC and a disregard for Doctor Who by senior administrators, this cluster of circumstances led BBC management to delay the resumption of filming by a year. All of the stories originally planned for Season Twenty-Three would be cancelled. Furthermore, it was made clear that Doctor Who would now have to justify its continued existence, or be removed from the schedules again -- permanently.

Season Twenty-Three (1986): On Trial

Companions and Recurring Characters

The Valeyard was a Time Lord who prosecuted the Doctor at his trial, until he was revealed to be some form of aberrant version of the Doctor from the future.

Michael Jayston (bio) played the Valeyard in The Trial Of A Time Lord (September to December 1986).

The Valeyard

The Inquisitor was a Time Lord who presided over the Doctor's trial with cold efficiency.

Lynda Bellingham (bio) played the Inquisitor in The Trial Of A Time Lord (September to December 1986).

The Inquisitor

Sabalom Glitz was an intergalactic mercenary and pirate who sometimes helped and sometimes hindered the Doctor -- but always with his own best interests in mind.

Tony Selby (bio) made his first appearance as Glitz in The Trial Of A Time Lord (September 1986) and his last in Dragonfire (December 1987).

Sabalom Glitz

Melanie Bush, also known as Mel, was a computer programmer from Earth gifted with an eidetic memory.

Bonnie Langford (bio) made her first appearance as Melanie in The Trial Of A Time Lord (November 1986) and her last in The Giggle (December 2023).

Mel Bush

The Production Team

The rapport between John Nathan-Turner and Eric Saward had been slowly deteriorating for years, but the tumultuous production of Season Twenty-Three placed new strains on their relationship from which they were unable to recover. Fed up with a series of decisions to which he strenuously objected, Saward quit Doctor Who. This forced Nathan-Turner to assume the dual roles of producer and script editor for the latter part of the troubled season.

The Stories
The Trial Of 
A Time Lord (Segment One)
The Trial Of A Time Lord (Segment One) by Robert Holmes, directed by Nicholas Mallett
An amnesiac Doctor is put on trial for his life by a Time Lord Inquisitor. The prosecutor, the sinister Valeyard, uses the Matrix to show the court the Doctor's recent adventure on the planet Ravolox. There, the robot Drathro rules an underground civilisation, but is now malfunctioning after centuries of operation. On the surface live the warlike Queen Katryca and her Tribe of the Free. They capture Peri and imprison her with Glitz and Dibber, two off-world conmen who have come to steal Drathro's secrets. Meanwhile, the Doctor discovers evidence of an impossible connection between Ravolox and Earth.
The Trial Of 
A Time Lord (Segment Two)
The Trial Of A Time Lord (Segment Two) by Philip Martin, directed by Ron Jones
At the Doctor's trial, the Valeyard presents the Doctor and Peri's most recent adventure. On the trail of arms merchants, they arrive on Thoros-Beta, home of the Mentors -- including their old foe, Sil. There they are attacked by a genetically-modified monster created by the scientist Crozier. He is searching for a way to save Kiv, the Mentor leader, whose enhanced intelligence is now causing his brain to outgrow his skull. Peri forges a reluctant alliance with a brash and headstrong warlord named King Yrcanos. But the Doctor is subjected to mind-altering technology... and appears to cast his lot with Crozier and the Mentors.
The Trial 
Of A Time Lord (Segment Three)
The Trial Of A Time Lord (Segment Three) by Pip and Jane Baker, directed by Chris Clough
To make the case for the defence at his trial, the Doctor presents an adventure from his future, when a distress call summons the TARDIS to the space liner Hyperion III. His new companion, Melanie, witnesses a crewmember die in the booby-trapped Hydroponics Centre, only for the body to disappear. The Doctor unmasks an alien Mogarian as an undercover agent -- who is promptly murdered. The ruthless Professor Lasky and her team are keeping secrets in an isolation room. Lurking in the shadows are the sinister plant-like Vervoids. And, in the courtroom, the Doctor realises that the evidence is being manipulated...
The Trial 
Of A Time Lord (Segment Four)
The Trial Of A Time Lord (Segment Four) by Robert Holmes and Pip and Jane Baker, directed by Chris Clough
Melanie Bush and Sabalom Glitz suddenly appear at the Doctor's trial, summoned by the Master. He reveals that the proceedings are part of a conspiracy by the corrupt High Council of the Time Lords, who ravaged the Earth and renamed it Ravolox in order to hide the theft of Matrix secrets. Furthermore, the Valeyard is actually the distillation of the Doctor's evil side between his twelfth and final regeneration, and has been promised the Doctor's remaining lives. The Doctor pursues the Valeyard into the Matrix, where he must navigate the bewildering Fantasy Factory -- but the Master has plans of his own.
At the conclusion of the trial, it is revealed that Peri has married King Yrcanos. Melanie travels on with the Doctor.

Making History

When Doctor Who finally returned from its hiatus, it had reverted to a twenty-five-minute format, but with a substantially reduced episode count. Consequently, the year-long trial storyline was formulated to parallel Doctor Who's own plight. Unfortunately, script problems plagued the new season before it even reached the screen, and ratings dwindled below the disappointing levels of 1985. Determined to shake up the programme, BBC management ordered Colin Baker's dismissal, but agreed to another season with a new Doctor. Doctor Who was not out of hot water yet by any means...