The triumvir monetalis (pl. tresviri or triumviri monetales, also called the triumviri (tresviri) aere argento auro flando feriundo, abbreviated IIIVIR A. A. A. F. F.) was a moneyer during the Roman Republic and the Empire, who oversaw the minting of coins. In that role, he would be responsible for the "ordinary coinage" during the republican period (contrasted to extraordinary coinage, usually minted by other magistrates, done on an ad hoc basis). Roman moneyers almost always acted together as a board of three, hence their title triumvir.
Over the course of the late Republic from 139 BC onwards, the moneyers started to mint more personalised coins which advertised their lineages, achievements of ancestors, and other leaders. From Caesar's dictatorship onwards, however, their freedom to do so diminished, before the empire's emergence coincided with the minting only of coins depicting the emperor and the imperial family.
The office continued into the imperial period as an administrative post.