The Ood
The Ood were first seen in The Impossible Planet (Series 2 : Episode 8) and The Satan Pit (Series 2 : Episode 9) as a humanoid species enslaved by the humans to carry out menial tasks. The Ood had coleoid tentacles on the lower halves of their heads, and communicated with telepathy due to having no vocal chords. They have a long lifespan, with Ood Sigma living for a hundred years after the end of the Ood enslavement. The Ood had two brains, one inside their head (a forebrain) and one outside of their body, a secondary hindbrain. The hindbrain is connected to the Ood by an umbilical cord-like connection to their faces. The hindbrain was removed from the Ood and replaced with a translator allowing them to communicate with humans. Originally a hive mind species led by the Ood brain, the humans severed this connection by replacing the hind brain with translation spheres, limited their telepathic communications field to “Basic 5”, cutting them off from communicating with the Ood brain. The colour of an Ood’s eyes reflects the level of telepathic communications it is able to do.
Prior to the 39th century, the Ood were a peaceful herd race until the humans enslaved them. The Ood were then dispatched across the three galaxies of the Second Great and Bountiful Human Empire to perform menial tasks. The method employed by Ood Operations to produce servile Ood was kept a secret from humanity, deceiving them into believing that the Ood offered themselves willingly as slaves. By the 42nd century, it was believed that every human had an Ood slave, generally barely regarded as being alive and were also considered expendable, however an activist group called Friends of the Ood fought for the cause of Ood freedom. In 43K2.1, the Doctor, along with Rose Tyler, first met the Ood on the planet of Krop Tor on Sanctuary Base 6. The Ood were slaves to the humans working on Sanctuary Base 6, but become possessed by the Beast that lived on the planet, who turned the Ood into his legion. As such, our first encounter with the Ood would have them seen as enemies of the Doctor, however it was just down to them being possessed that caused them to act menacingly towards the Time Lord and the humans. The Ood were stopped when Danny Bartock reset their communications level to “Basic 0”, creating a brainstorm which reset the Ood. Though they passed out, their telepathic field did begin to return before Krop Tor was swallowed by the black hole. The Doctor was unable to save any Ood when Krop Tor was sucked into the black hole. All of the Ood on Sanctuary Base 6 perished but were given posthumous honours.
In 4126, the Doctor and Donna Noble visited the Ood’s home planet, the Ood Sphere to see how the Ood were made to be willing slaves and discovered the horrible truth. At the same time, a disease known as ‘red-eye’ was becoming common among the Ood, which was discovered to be caused by the Ood Brain’s subconscious reasserting itself over the Ood. The Doctor then deactivated the field that was suppressing the Ood Brain’s telepathy, which sent out a song for everyone to hear across the three galaxies. When humanity realised the truth about their Ood, they freed them and returned them to the Ood Sphere to live a happy life. Around 4226, the Ood had advanced unnaturally fast, building entire civilisations and extending their mental abilities; however with this came nightmares of time bleeding and a mysterious face. Ood Sigma was sent to find the Doctor and bring him to the Ood Sphere where they showed him the face of the Master, who returned to 21st century Earth to investigate. The Ood were there when the Doctor regenerated into his eleventh incarnation and telepathically sang for him.
In The Doctor’s Wife (Series 6 : Episode 4), a modified Ood, named Nephew, is seen on the asteroid House. Nephew had a green translator and green eyes, possibly due to House’s influence upon him. House ordered Nephew to kill Amy Pond and Rory Williams when they were trapped inside the TARDIS but he was squashed when the Doctor and Idris landed another TARDIS inside the Doctor’s TARDIS.