biographer (n.)
1715; see biography + -er (1). Earlier was biographist (1660s).
Of every great and eminent character, part breaks forth into public view, and part lies hid in domestic privacy. Those qualities which have been exerted in any known and lasting performances may, at any distance of time, be traced and estimated; but silent excellencies are soon forgotten; and those minute peculiarities which discriminate every man from all others, if the are not recorded by those whom personal knowledge enabled to observe them, are irrecoverably lost. [Johnson, "Life of Sir Thomas Browne," 1756]