BIOGRAPHY & PROSOPOGRAPHY

 The following are authoritative starting points for biographical information:

Cambridge dictionary of classical civilization (2006) [print] 
[Survey of the classical world from post-Bronze Age Greece to the end of the later Roman Empire]

Oxford classical dictionary (3rd edition, 1996) [print]
[A comprehensive  source of information covering all aspects of the classical world]

Brill's New Pauly : encyclopaedia of the ancient world, (on-going) [print]
[Publication of the English language version of this classic reference work will proceed over a number of years. The complete work is available in German, as are Pauly's 19th century original work and the second series] 

Other sources for biography can be identified through this catalogue search, & more subject-specific biographical sources (where available) can be identified in individual Subject guides.

For works about prosopography and names generally in the Classical World try this catalogue search.

A useful biographical source for classical scholars is:

Classical scholarship : a biographical encyclopedia (1990) [print]
[Biographies of 50 influential classical scholars from the 1800s to the present]