Engin

Engin was a Time Lord who served as Coordinator of the Matrix. He retired and sat as an Independent on the High Council, later returning to his role (now known as Keeper) by the time of the Last Great Time War.

Early life
Like all Time Lords, Engin was taken from his family at the age of eight for the selection process in the Drylands. Staring into the Untempered Schism as part of a Time Lord initiation rite, Engin was inspired by what he saw in the Schism. (PROSE: A Brief History of Time Lords)

Career at the Archives
Engin worked in the Records Section, firstly as a humble data Recorder. Over several centuries and numerous regenerations, he slowly rose through the ranks and became Coordinator of the Matrix. (PROSE: Doctor Who and the Deadly Assassin)

By the time that had Chancellor Goth assassinate President Pandad IV, he was in his twelfth incarnation. Many people pressed him to regenerate into a younger form, but, loath to expend his final life, Engin kept putting off for "a year or two" over and over, noting that he did not need the strength of youth given he hardly ever left the computer area. (PROSE: Doctor Who and the Deadly Assassin) Following the assassination of the Lord President by Goth, he explained the nature of the Matrix to the Fourth Doctor so that the Doctor could follow Goth into the Matrix and defeat him there. After the Master was defeated, he was put on the Committee of Inquiry. (TV: The Deadly Assasin)

As a Councillor
Coordinator Engin was considered very old during Flavia's time as Acting President and he retired. He sat on the High Council as an Independent councillor, unaffiliated with President Niroc. The Sixth and Eighth Doctors selected him when arranging an inquiry in the Sixth Doctor's trial, reasoning that he might be old but he possessed a clearer knowledge of the Matrix than any other. (PROSE: The Eight Doctors)

The Time War
Engin was again Keeper of the Matrix during the Last Great Time War. He spoke with Priyan about the Doctor's actions and how the War would end. (COMIC: Sky Jacks)

Personality
Engin was brisk, efficient and curious. (PROSE: Doctor Who and the Deadly Assassin) The Eighth Doctor thought that he was very intelligent, with unrivalled knowledge of the Matrix. (PROSE: The Eight Doctors)

Appearance
In his twelfth incarnation, by the time of the 406th President's assassination, Engin's body was almost worn-out and his final regeneration seemed long overdue. He had snowy-white hair, was bent and shrunken with age and had a face "wrinkled like an old apple" but with eyes alive with curiosity. (PROSE: Doctor Who and the Deadly Assassin)

Behind the scenes

 * Engin appears in NOTVALID: Incoming Transmission, having regenerated into a body played by Dan Starkey. This would appear to be the aforementioned final thirteenth incarnation.