Postar

Postar the Perfidious was the author of the Scrolls of Gallifrey, a history of the planet Gallifrey and the life of Rassilon up to the events of Flavia's ascension to the Presidency of the Time Lords.

The Scrolls were written a language which, after much efforts, a team of human translators were able to decode after fragments of the documents ended on Earth by means unknown. (PROSE: The Legacy of Gallifrey)

Behind the scenes

 * Postar's species remains ambiguous; the amount of his knowledge on Gallifreyan history might suggest a Time Lord, though his writing speaks of "the Time Lords" and "the Gallifreyans" in the third person plural, without ever identifying himself with them.
 * The epithet of "the Perfidious" may be intended to suggest to the reader that Postar is an unreliable narrator and that the history of Gallifrey presented through the Scrolls in The Legacy of Gallifrey is somewhat suspect.