Marcus Tullius Tiro, the narrator in Robert Harris' novel, Imperium: A Novel of Ancient Rome, was Cicero's slave secretary and later freedman. Here is a little Wikipedia (as usual handle with care) page. He supposedly lived to the age of 99.
He is thought to have collected and published Cicero's work after his death, and several ancient writers refer to works by Tiro himself also, now lost. His other claim to fame is the tradition that he invented the shorthand. Although it seems that the initial honor should go to Xenophon, according to a Britannica online article, shorthand. (Another site has an image supposedly representing Tironean shorthand.) Postscript later today: See comments below for further elucidation. A warning: The Manuscript site is not easy to navigate.
Tiro appears as a supporting character in novels and mysteries about the late Republic.
