Shepherd and Shepherdess

From Tardis Wiki, the free Doctor Who reference

The Shepherd and Shepherdess were a pair of beings who could travel between universes destroying them in their wake. They didn't care for the small beings. They came to the Seventh Doctor's universe during World War II in Nazi Germany. They explored Dusseldorf, and it made them sad. They gave Kurt Schalk the ideas for the persuasion machine, so that they could remodel the universe in their image. They absorbed people to feed their hunger and only left ashes. The Seventh Doctor tried to stop them from being evil by showing them the most beautiful planet in existence, but tricked them into living on New Peerlessness, a prison planet, which the Doctor placed in his TARDIS. (AUDIO: Persuasion) The Shepherdess died in this prison. (AUDIO: Daleks Among Us)

Will Arrowsmith released the Shepherd thinking that he could help in stopping the Daleks, but was mistaken. Elizabeth Klein used the machine to kill the Shepherd. (AUDIO: Daleks Among Us)