Darkel

Inquisitor Darkel served on the High Council of Gallifrey.

Biography
Darkel presided over the Doctor's trial on the Time Lord Space Station Zenobia, with the Valeyard acting as prosecutor. (DW: The Mysterious Planet, DW: Mindwarp) The Doctor himself would at a later stage act as his own defense lawyer. (DW: Terror of the Vervoids) (The Valeyard himself, apparently an independent Time Lord represented a dark side of the Doctor's personality.)

An honest woman, Darkel presided over a show trial designed to draw attention away from the corrupt High Council. With political unrest demanding a new Lord President and the Doctor unwilling to take on the job himself, he gave a symbolic vote of confidence to Darkel himself before departing in his TARDIS. (DW: The Ultimate Foe)

Behind the Scenes
On-screen Darkel had no name given to her, other than "the Inquisitor". The name Darkel was given to her in the Big Finish Doctor Who audio spin-off sereis Gallifrey.