Inquisitor
An inquisitor was a Gallifreyan judge (TV: The Mysterious Planet, etc.) and an officer of the Inquisition. (AUDIO: Lies) The most senior judge was called Inquisitor Prime. (AUDIO: The Inquiry)
History
In the second session of the Second Doctor's trial, he was questioned one-on-one by an Inquisitor. As the Doctor summarised everything he had done after leaving Victoria Waterfield, a pattern emerged of the planet Earth being a frequent site of alien invasion. From this, the Inquisitor decided that the Doctor should be exiled to Earth. (PROSE: Second Session)
During the judicial inquiry into the Sixth Doctor on the Space Station Zenobia, Darkel assumed the role of inquisitor. (TV: The Mysterious Planet, etc.) She later did the same for the Valeyard's trial (AUDIO: Trial of the Valeyard) and for the attempted impeachment of President Romana. (AUDIO: The Inquiry)
The Eleven asked Kiani if she wanted to be an inquisitor. However, she had further ambitions and wanted to do something more "hands on". (AUDIO: The Eleven)