We know next to nothing about the life of another biographer, Diogenes Laertius. We're not even sure which century he lived in: the third century A.D. is the most likely, but the fourth century A.D. is also possible. He wrote a series of lives of Greek philosophers prefaced by an essay on the origins of philosophy and different ways of classifying philosophers. As far as I know the Greek text of his work is not on the internet yet, but there is a 19th century translation by C. D. Yonge at Peitho's Web
. Loeb has the Greek text and a facing English translation in two volumes.
The Augustan History is a series of biographies of the emperors from Hadrian to the brothers Carinus and Numerianus (covering a period from 117-285 A.D.), and may have been written as a deliberate continuation of Suetonius? Lives of the Caesars. It purports to be a compilation written by six authors (Aelius Spartianus, Julius Capitolinus, Aelius Lampridius, Vulcatius Gallicanus, Trebellius Pollio and Flavius Vopiscus) in the reigns of Diocletian (284-305 A.D.) and Constantine I (306-337 A.D.). Many historians, however, believe that it was in fact the work of a single author who lived at the end of the fourth century or even later. The Latin text can be found at the Latin Library
. There does not seem to be any complete translation into English on the internet, although there are translations of the lives of individual emperors in various places. Penguin Classics has a translation by Antony Birley of the biographies of the emperors from Hadrian to Heliogabalus, together with two modern compilations of lives of Nerva and Trajan, under the title Lives of the Later Caesars. Loeb has the complete Augustan History in three volumes, with the Latin text and a translation by D. Magie on facing pages.
Note: The above is slightly adapted from two articles which have previously appeared at http://www.suite101.com/welcome.cfm/ancient_biographies