The Sensorites is the seventh serial of the British science fiction television series Doctor Who. Written by Peter R. Newman and directed by Mervyn Pinfield and Frank Cox, the serial was first broadcast on BBC1 in six weekly parts from 20 June to 1 August 1964. In the serial, the First Doctor (William Hartnell), his granddaughter Susan Foreman (Carole Ann Ford), and her teachers Ian Chesterton (William Russell) and Barbara Wright (Jacqueline Hill) visit a planet known as the Sense-Sphere to find the cure to a disease afflicting the alien race the Sensorites.

Newman's story for the serial was inspired by 1950s films set during World War II, exploring the notion of soldiers who continued to fight after the war. Pinfield was chosen to direct the first four episodes due to his directing style, while Cox directed the final two episodes. Designer Raymond Cusick avoided the use of right angles in his set designs, recalling Antoni Gaudí's work on the Sagrada Família. The serial premiered with 7.9 million viewers but failed to maintain these figures due to the holiday sports season. Retrospective response for the serial was generally positive, and it later received several print adaptations and home media releases.

The TARDIS crew land on a spaceship, where they meet crew members Captain Maitland (Lorne Cossette) and Carol Richmond (Ilona Rodgers), who are on an exploration mission from Earth and are orbiting Sense-Sphere. However, its inhabitants, the Sensorites, refuse to let them leave orbit. The Sensorites visit and stop the travellers from leaving while sending them on a collision course, which the First Doctor (William Hartnell) diverts. The travellers then meet Carol's fiancé John, whose mind has been broken by the Sensorites. Susan Foreman's (Carole Ann Ford) telepathic mind is flooded with the many voices of the Sensorites who remain scared of the humans and are trying to communicate with her.

Meanwhile, the Doctor calculates that the Sensorites attacked the human craft because John (Stephen Dartnell), a mineralogist, had discovered a vast supply of molybdenum on Sense-Sphere. Susan reports that the Sensorites wish to make contact with travellers, asking the crew to board Sense-Sphere and reveal that a previous Earth expedition caused them great misery. The Doctor asks the Sensorites to return the TARDIS' lock in exchange for visiting the Sense-Sphere to speak with the leader; Ian Chesterton (William Russell), Susan, Carol, and John join him.

On their journey to Sense-Sphere, the party learns that the previous visitors from Earth exploited Sense-Sphere for its wealth; half of them stole the spacecraft, which exploded on take-off. The Sensorite Council is divided over the issue of inviting the party to Sense-Sphere: some members plot to kill them on arrival, but others believe that the humans can help with the disease that is currently killing many Sensorites. When their first plot is foiled by other Sensorites, they continue to plot in secret. John's mind is eventually unblocked. Ian contracts the disease that has blighted the Sensorites, and told that he will soon die; it is revealed that he was actually poisoned by drinking water from the aqueduct. The Doctor finds the aqueduct and creates a cure for Ian. The plotting Sensorites capture and then impersonate a Sensorite leader, the Second Elder (Bartlett Mullins).

Meanwhile, investigating the aqueduct, the Doctor finds strange noises and darkness. He sees and removes deadly nightshade, the cause of the poisoning, but while returning meets an unseen monster. Susan and Ian find him unconscious but unharmed. On recovering, he tells of his suspicion that some Sensorites are plotting to kill them. The plotting Sensorites kill the Second Elder and one of them replaces him in his position. John tells the others that he knows the lead plotter, but he is now too powerful, so the Doctor and Ian go down to the aqueduct to find the poisoners. Elsewhere, a mysterious assailant abducts Carol; Susan, John, and Barbara Wright (Jacqueline Hill) eventually find and release her. On discovering the tampered tools, they go into the aqueduct to rescue the Doctor and Ian. The leader discovers the plotters a little while later. Ian and the Doctor discover that the monsters were actually the survivors of the previous Earth mission, and they had been poisoning the Sensorites. Their deranged Commander (John Bailey) leads them to the surface, where they are arrested by the Sensorites. The Doctor and his party return to the city, pleading clemency for the poisoners. The leader of the Sensorites agrees and sends them back with Maitland, John, and Carol to Earth for treatment.

Peter R. Newman developed the concept for The Sensorites in January 1964 and was officially commissioned to write the serial on 25 February by script editor David Whitaker. Newman's story was inspired by 1950s films set during World War II, exploring the notion of soldiers who continued to fight after the war. Mervyn Pinfield was chosen to direct the first four episodes, as it was felt that he could evoke great visual atmosphere despite a small budget, while Frank Cox directed the final two episodes.

Stephen Dartnell, who had previously appeared in The Keys of Marinus, was chosen to portray John, while Ilona Rodgers played his fiancée Carol. Canadian actor Lorne Cossette played Maitland, and John Bailey portrayed the Commander; Cox envisioned the Commander akin to Ben Gunn, a character from Robert Louis Stevenson's Treasure Island, and cast Bailey after seeing him in the play Pygmalion in April 1962. The other human survivors were played by Martyn Huntley and Giles Phibbs, friends from drama school who knew the director's secretary and were scheduled an interview.