Jelpax

Jelpax was a Time Lord contemporary of the Doctor and coordinator of the APC Net. He did not become a renegade, instead remaining on Gallifrey

Academy years
According to a dream the Fifth Doctor experience while under the influence of the Celestial Toymaker, during which he thought himself back on Gallifrey in the younger years of his first incarnation, Jelpax was a member of the Deca alongside the Doctor, Drax, Vansell "Koschei", "Magnus", Ushas, Mortimus, Millennia and Rallon. When the Doctor faced expulsion for his unlawful escapades, Jelpax assured him that he had not been the one to turn him in; though he disapproved of the Doctor's rash actions, Jelpax claimed to admire him nonetheless for the strength of his convictions. (PROSE: Divided Loyalties)

Career as a coordinator
Jelpax became one of the major recorders of Gallifrey, keeping an eye on matters in "four or five minor galaxies" as the coordinator of the APC Net. His team foresaw a universe in which the Daleks would become the dominant lifeform in the universe and constructed a plan to stop it, (PROSE: Divided Loyalties) sending the Fourth Doctor back in time to the Thousand Year War between the Thals and the Kaleds to try and prevent the Daleks ever arising, or, at the very least, altering their developments so that they matured into a more peaceful species. (TV: Genesis of the Daleks) This ill-fated plan was ultimately helpless to prevent an eventual war between Gallifrey and Skaro which ended with the temporary annihilation of Time Lord supremacy. (TV: Dalek)

Fall from grace
Throughout his life he remained a staunch supporter of Lord Cardinal, later Lord President Borusa, his former teacher. Borusa was only made aware of the many artefacts from the Dark Times (PROSE: Divided Loyalties), such as the Ring of Rassilon, the Black Scrolls of Rassilon or the Coronet of Rassilon, (TV: The Five Doctors) from Jelpax. Realising his connection to Borusa's betrayal, Jelpax was removed from his posting and ended up on monitoring duty. (PROSE: Divided Loyalties)

Behind the scenes

 * While it definitely places Jelpax as the originator of the scheme seen in Genesis of the Daleks, Divided Loyalties is not quite explicit on whether the actual Time Lord messenger who contacts the Doctor in the opening to said story, played by John Franklyn-Robbins, should be understood to be Jelpax. Other stories variously identified Franklyn-Robbins's TIme Lord character as Lord Cardinal Valyes or as the C.I.A. Director, Ferain.