Cardinal Ollistra was a high ranking Time Lord involved in the Last Great Time War.
Through her lives, Ollistra was a heartless politician. (AUDIO: The Innocent, The Side of the Angels)
Late in her lifetime, one of Olistra's last incarnations (AUDIO: The Conscript) was a part of the High Council, and had dealings with the Doctor, both in his seventh (AUDIO: Dark Universe) and eighth incarnations. (AUDIO: The Side of the Angels)
In her next incarnation, Ollistra was a part of the War Council, and was a forefront of the Time Lord's efforts against the Daleks during the Last Great Time War. Initially, she tried to get the Eighth Doctor to join the ranks, (AUDIO: Echoes of War, The Conscript) and by the time he regenerated into the War Doctor, she actively joined him in several missions, much to his chagrin (AUDIO: The Innocent, et al.)