- You may be looking for the Central Committee of Mondas.
The Committee was a group of aliens based on the planet Erebus.
The Committee was actually created on the initiative of Queen Victoria and Tsar Alexander in the late 19th century. They gathered a group of aliens that were to appear as a threat to the two countries' respective institutions – Torchwood and KVI and in this way test them and exercise Earth's defences in exchange for captured technology. However, the Committee got out of hand and started invading other worlds in its own right, becoming an actual threat. (AUDIO: The Torchwood Archive)
They took over planets in Signus A, Omega Centauri, and Andromeda. Jack Harkness met them on Kepri 5 in the constellation of Fornax, where he told them that Earth had no intelligent life. (AUDIO: The Conspiracy)
In the late 2000s, the Committee came back to Earth. One of them assumed the name "Kate" and became the adopted daughter of journalist George Wilson. She told him real things about the Committee to put in his conspiracy theory books. When Sam Hallett got too close to the truth, she killed him and made it look like a suicide. Jack discovered Kate's nature, and went to confront her about Sam's death, but Kate killed George and left Jack to be discovered by the police. Jack fled, and left a recording for the Torchwood team to explain the situation. (AUDIO: The Conspiracy)