all manner of menial tasks for the humans in the episode. They are described as offering themselves for servitude willingly, having no goals of their own except to be given orders and to serve. It is also claimed that they cannot look after themselves and that, if they do not receive orders, they pine away and die. The episode also alludes to a protest group called "Friends of the Ood" who oppose Ood slavery and seek to have them freed. According to the Official Doctor Who Annual 2007, the Ood live on a planet in the Horsehead Nebula, where they were governed by a Hive Mind that was destroyed by human colonists. The BBC-authorised book Doctor Who: Creatures and Demons elaborates that the Ood came from the Ood Sphere. The Ood Sphere is close to the Sense Sphere planet, home to the Sensorites, who share a mental and physical similarity with the Ood. Without a hive mind, the Ood offered themselves to the human colonists and became a slave race. The Tenth Doctor and Rose Tyler encounter fifty Ood accompanying a human-led expeditionary force in "The Impossible Planet". The empathic nature of the Ood made them susceptible to psychic possession by the Beast, who formed the Ood on the base into his "Legion". While possessed, the Ood's eyes changed color to red and they killed several humans by throwing their translation spheres at them and electrocuting them. At the end of the episode, the Doctor was forced to sacrifice all the surviving Ood to the black hole around the planet because he did not have time to save both them and the human crew. The Ood return in the Series 4 episode "Planet of the Ood", where it is revealed that they are not born to serve but are an enslaved race. The Ood translation spheres actually replaced their hind brain which had contained their individual personalities. The Doctor successfully frees the Ood by releasing the Ood hive mind, which connects all the Ood with a telepathic link. The hive mind had been sequestered from the Ood for 200 years by Ood Operations, the corporation that processed the Ood slaves; however, the Ood known as Sigma, who appears as the personal servant of Ood Operations leader Halpen, has been advancing the Ood freedom, by slowly turning him into an Ood and lowering the barrier around the giant brain that links