Niroc

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