The Sensorites possessed bulbous heads with large black eyes which had no eyelids and, according to the First Doctor, their eyes were also dilated. They had white whiskers around their mouths. Their feet were very broad and flat. They were sensitive to loud noise and feared the dark; due to a unique feature of their eyes, they were left blind in the dark as well as terrified. Unlike humans, whose hearts were on the left, the Sensorites' hearts were located in the centre of their chest. (TV: The Sensorites)
The Sensorites' society was based on trust. They had a great deal of trust among themselves and found it hard to believe that any of them would break the trust of another. When trust was broken, it was seen as a very serious offense and could result in a removal from rank or banishment.
The Sensorites had a caste system. The Elders would think and rule, the Warriors would fight, and the other Sensorites would work and play. They did not view being in any caste as shameful, and thought that each caste was simply what job a person was best suited for. Because they appeared almost identical, even to themselves, they wore accessories with their otherwise identical grey bodysuits to denote various ranks: (TV: The Sensorites)
- First Elder — Two crossing black sashes
- Second Elder — Single black sash
- City Administrator — Black collar
- Scientist — Swirling pattern insignia on chest
- Warrior — Three black bands on forearms
The Sensorites had shown the ability to both communicate verbally and telepathically though they appeared to used the latter more for private conversation or if they wish to converse with someone a great distance away, in which case they used a flat communication disc to their forehead.
They were able to receive quite well without the disc, but they did require it to send telepathic messages. The Sensorites had also shown that they could use their telepathy to control their crafts, or blank out the minds of other beings. The number of telepathic frequencies covering the surface of the Sense Sphere were numerous. However, they could be disoriented by a concerted mental attack.
When the Sensorites had their backs turned, it was difficult to see who was who, as Carol Richmond discovered when she inadvertently mistook the City Administrator for the Sensorite scientist who was treating John. (TV: The Sensorites)
Early in their history, the Sensorites worshipped the Zilgans, since they lived in the darkness that they feared. They would feed them criminals and would be left on their own. The First Doctor accidentally arrived on the planet in a cave of a Zilgan. He was able to kill it. When the Sensorites learned of this, they planned to kill him. With the help of Tony and Amy Barker, he was able to scare them off by shouting and was able to escape. (PROSE: The Monsters from Earth)
In the 28th century, an exploration mission from the Earth Empire made contact with the Sensorites and attempted to exploit their world's mineral wealth. The humans appeared to die when their spacecraft exploded and the Sensorites began to suffer a plague shortly afterwards.
Years later, when a second exploration mission from Earth arrived, the Sensorites feared they would also attempt to exploit them and held them prisoner aboard their own ship. The situation was resolved by the First Doctor and his companions, who made peace between the Sensorites and the humans, and revealed that the plague was actually atropine (or Atropa belladonna) poisoning caused by the insane survivors of the first expedition. (TV: The Sensorites)
Lucie Miller encountered the Sensorites during her travels with the Monk. She later told the Eighth Doctor that they were "not as much of a laugh" as the "well bonkers" Roman Emperor Caligula. (AUDIO: The Resurrection of Mars)
During the Last Great Time War, three Daleks visited the Sense Sphere, claiming to need parts for their craft. Using their telepathic abilities, the Sensorites turned the Daleks against each other, unaware that they'd planted a Dalek mutant mixed with Sensorite DNA into the Interior. Unable to match the Sensorites' telepathy directly, the Daleks had bred the creature to increase the Sensorites' paranoia.
After the Daleks had seized control of a TARDIS, Susan Foreman suggested that the Time Lords seek out the Sensorites' aid to reconnect with the ship's telepathic circuits. Accompanied by Ian Chesterton, Susan returned to the Sense Sphere to negotiate their aid. Once the two had defeated the Dalek creature, the Sensorites, now readily convinced of the Dalek threat, offered their aid and used their telepathy to trigger the stolen TARDIS's self-destruct. (AUDIO: Sphere of Influence)
When cyborg hacker Psi was attempting to protect Clara Oswald from the Teller, he ensured that it would focus on his guilt by uploading the memories of some of the worst criminals in history, one of them being a Sensorite. (TV: Time Heist)
Behind the scenes
Russell T Davies has acknowledged the Sensorites as an influence on the basic concept of the Ood in The Impossible Planet and The Satan Pit. Computer read-outs (TV: Planet of the Ood) and a mention by Davies in an episode commentary [which?] revealed that the Ood Sphere and the Sense Sphere are part of the same star system.