In his Vita divi Augusti, Gaius Suetonius quoted four terms which were in use in ancient Rome and referred to bankers: argentarii, mensarii, nummularii and coactores argentarii. In his description of the life of Emperor Augustus, the historian mentions the rumour that the Emperor’s grandfather was engaged in usury. However, in the excerpts focusing on the genealogy of Augustus, Suetonius applied the term argentarius, which undoubtedly denoted a banker running his operations, in a professional manner, in the Forum or in another public place. Thus, the ancestors of the princeps could have been involved in specialised activities, supervised by officials and subject to particular obligations. This assumption is corroborated, among others, by the fact that the Emperor’s father, Gaius Octavius, enjoyed general public esteem. Similarly, the unintended comparison, by Cassius of Parma, of the princeps’ grandfather to mensarii or nummularii may confirm the hypothesis that he was neither a money-changer nor a moneylender. Among the ancestors of other emperors, such as Emperor Vespasian, there were also bankers referred to as coactores argentarii who conducted auctionrelated activities, and this is exactly the type of banking activity that his father and grandfather were involved in. Therefore, Suetonius was aware of various terms used in ancient Rome to describe the banking profession.