The Krotons


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The Krotons

Serial Code


First Transmitted

28 December 1968

Final Ratings







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Regular Cast

Patrick Troughton (Dr Who), Frazer Hines (Jamie), Wendy Padbury (Zoe)

Guest Cast

James Copeland (Selris), Terence Brown (Abu) [1], Madeleine Mills (Vana), Gilbert Wynne (Thara), Philip Madoc (Eelek) [1, 3-4], Richard Ireson (Axus) [1, 3-4], James Cairncross (Beta) [1, 3-4], Bronson Shaw (Student) [1], Maurice Selwyn (Custodian) [1], Roy Skelton, Patrick Tull [2-4] (Kroton Voices), Robert La’Bassiere*, Miles Northover (Krotons) [2-4].


Written by Robert Holmes
Directed by David Maloney
Produced by Peter Bryant


As the TARDIS door opens onto a barren planet, The Doctor steps straight into a struggle to destroy the merciless Krotons, the unseen rulers of the Gond people.

Conditioned to obey by teaching machines, the Gonds put up no resistance until, with The Doctor’s help, they discover exactly what has been happening to their best students.

Battling against the Krotons’ vast scientific knowledge The Doctor and Zoe must stop them turning mental power into pure energy. With a brave band of Gonds and Jamie, prepared to fight to the end, it may be defeat for the Krotons, but ultimately it will be a test of knowledge that only The Doctor can match


On an unnamed planet, a race called the Gonds are subject to the mysterious Krotons, unseen beings to whom they provide their brightest intelligences as “companions”. Thara, son of the Gond leader Selris, is the only one of his race to object to this practice, those who have become companions before have never been seen nor heard from again. The Doctor, Jamie and Zoe arrive in time to witness the death of one of the chosen companions, Abu, who is vaporised by smoke sprayed from nozzles on either side of the doorway from which he emerges, and intervene to save Vana, the other selected for this fate, using her survival as a means to convince Selris and the Gonds of the malign influence of the Krotons on their society. The Doctor calls it “self-perpetuating slavery” by which the brightest in Gond society have been removed. Similarly, there are large gaps in their knowledge, especially relating to chemistry. This situation has been in existence for many years since the Krotons arrived in their spaceship, releasing a poison that polluted the lands beyond the Gond city – which the Gonds call ‘the Wasteland’ – and killed much of the Gond population.

Thara uses the disquiet of the situation to lead a rebellion and attack the Teaching Machines of the Krotons in the Hall of Learning. This prompts a crystalline probe to appear and defend the Machines, and warn the Gonds to cease their rebellion. Zoe now tries the Teaching Machines and is selected to be a “companion” of the Krotons. The Doctor elects the same fate and both are summoned into the Dynotrope where they are subjected to a mental attack. Zoe deduces that the Krotons have found a way to transfer mental power into pure energy, while The Doctor busies himself with taking chemical samples of the Kroton environment. Circumstances now trigger the creation of two Krotons from chemical vats within the Dynatrope (the Kroton spaceship). The newly created Krotons capture Jamie, but are really seeking The Doctor and Zoe, the “High Brains”, who have now left the Dynatrope. It takes Jamie quite some time before he is able to make an effective escape.

Eelek and Axus, two councillors previously loyal to the Krotons, who begin to rally for all-out war with the Krotons, have now seized the initiative in Gond society. The more level headed Selris is deposed, but warns that an all-out attack will not benefit his people. Instead he has decided to attack the machine from underneath by destabilising its very foundation in the underhall. Eelek has Selris arrested and also reasserts control by negotiating with the Krotons that they will leave the planet if provided with the two “High Brains” who can help them power and pilot their ship. Zoe and the Doctor are forced into the Dynatrope and Selris dies providing them with a phial of acid which The Doctor adds to the Kroton vats. Outside, Jamie and the scientist Beta launch an attack on the structure of the ship using sulphuric acid. This two-pronged assault destroys the tellurium-based Krotons and their craft. The Dynatrope dissolves away and the Gonds are free at last – choosing Thara rather than the cowardly and ambitious Eelek to lead them.

Leaving the Gonds to find their own answers for the future, The Doctor, Jamie and Zoe slip away back to the TARDIS and new adventures.


  • The Krotons is the fourth serial of the sixth season of the British science fiction television series Doctor Who,
  • Popular Welsh actor Philip Madoc makes his first appearance in Doctor Who as Eelek.
  • Working titles for this story included The Trap and The Space Trap. Holmes had originally submitted The Trap to the BBC as a stand-alone science-fiction serial in 1965. 
  • Frazer Hines had originally intended to leave the series at this point but decided to stay on to the end of the season after he learned that Patrick Troughton would also be bowing out then. This was the main reason why a light-hearted story entitled The Prison in Space by Dick Sharples, in which Jamie was to have been written out and a new companion character called Nik introduced, was dropped at the last minute and The Krotons brought forward from later in the season to fill the slot.
  • First episode to be penned by Robert Holmes

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