Teselecta
The Teselecta was a humanoid starship/time machine. It was similar to an android that was staffed by a crew who had been miniaturised by a compression field. The Teselecta was used to locate people deemed guilty of crimes who had escaped punishment. In order to avoid changing history, once the guilty person was found near the end of their timeline, the crew of the Teselecta would admininster their own non-lethal painful torture form of punishment. Afterwards, they would die in the manner recorded by history.
Appearances
The Impossible Astronaut (TV)
Let’s Kill Hitler (TV)
The Wedding of River Song (TV)
The Partying of the Ways (Comic)