Niroc

Niroc was Lord President of the Time Lords after the Doctor was deposed during his long absence. It was believed that Niroc oversaw or took part in Operation Ravolox and had purposefully put the Doctor on trial to prevent the truth from coming out. His High Council enlisted the Valeyard, an evil version of the Doctor, to act as prosecutor and present fake evidence at the trial. In return he would receive the Doctor's remaining regenerations. When the Doctor was found innocent, Flavia, the adjudicator at the trial, became the next president. Niroc was a puppet of the Celestial Intervention Agency. (DW: The Trial of a Time Lord, EDA: The Eight Doctors)