The Endangered Dangerous Species Society also known as The Society for Endangered Dangerous Species was formed to hunt down dangerous species. Though ostensibly created to remove creatures which could pose a threat to others, it focused on wiping out creatures for fun. The Endangered Dangerous Species Society had wiped out over three hundred species (including the Irradiate Grinderstag and the Stellar Raptors) and was wanted by every security force in the Galaxy.
The members were brought to Planet 1 by Sebastiene to hunt down the Tenth Doctor. The twelve members would be sent to sections of the planet which had been remade into their preferred hunting grounds. The Doctor would be randomly teleported into a section, and if the member there failed to kill him, Sebastiene would kill them. Over the course of the hunts, all the members except the Carpalian Witch were killed by Sebastiene or each other. (PROSE: The Doctor Trap)
Membership could be gained by bringing in a trophy of a dangerous creature. Membership was limited to twelve.
At the time when Sebastiene summoned them to Planet 1, the Society's members included Brutus, Lord Percy, Commissar Weimark, the Carpalian Witch, the Semblance of Draxyx, Zzorg Zero, and Colonel Sty of the Bolkon Context. (PROSE: The Doctor Trap)