Seratrix

Seratrix was a military strategist for the Time Lords during the Last Great Time War. He was one of the top strategists on Gallifrey. However, he developed a belief that the only way to stop the war was to make peace with the Daleks. (AUDIO: The Thousand Worlds)

Ollistra sent him on the long way back to Gallifrey when she discovered a Dalek Time Ship on his trail. This act made him vulnerable to attack by the Daleks, which occurred. (AUDIO: The Innocent)

Seratrix had a belief that no one would survive the Time War, and the only way to stop it was to make peace with the Daleks. With this, he gathered some followers, including Bennus and Arverton. When Ollistra found out his beliefs, in order to stop the spread of it, she developed a scheme to kill Seratrix. She gave him the device that would create a temporal Null-zone that he could offer to the Daleks. Seratrix believed that the Daleks would be content with control of the worlds within the Null Zone while the Time Lords agreed to leave them alone, accepting their claim that the hollowed planets they were creating would be turned into mobile administrative stations while their populations were relocated.

When the War Doctor went to Keska to save him, Seratrix tried to convince him of his beliefs, but failed, the Doctor certain that the Daleks could never be trusted. Examining the Daleks' files, the Doctor learned that the Daleks' true plan was to use the hollowed planets and turn them into massive weapons, with the Daleks setting all thousand-plus worlds on a direct course to Gallifrey. Still pleading with the Dalek Prime for peace, Seratrix was killed, while the Doctor stopped the Daleks from drilling into the core of Keska. (AUDIO: The Heart of the Battle)