900 Year Diary

The Nine Hundred Year Diary was a journal kept by the Seventh Doctor. (TV: Doctor Who) It was presumably an updated version of his Five Hundred Year Diary. (TV: The Power of the Daleks, The Tomb of the Cybermen, The Sontaran Experiment) Eventually, the Doctor lived long enough to require an even further updated diary, as the Twelfth Doctor possessed a Two Thousand Year Diary. (TV: The Girl Who Died)