Pierre Bastien (1912-2010) was a French surgeon and numismatist who assembled a significant collection of Roman imperial coins that complemented his scholarly work. Although he was discrete about his collection and rarely discussed it, the collection was substantial and focused primarily on Late Roman imperial coinage, particularly from the period of Diocletian through Honorius. His collecting activities were intimately connected to his research.

Bastien stands as one of the most important scholars of Late Roman numismatics in the twentieth century. His work included an eight-volume series on the Lyon mint and a three-volume study on the coin busts of Roman emperors, establishing him as the foremost authority on the coinage of this critical period. His scholarship was distinguished by meticulous die studies and systematic mint analysis, beginning with his specialization in the coinage of the usurper emperor Magnentius in 1955 and expanding to encompass the entire Late Roman period from Diocletian through Honorius. Many of his monographs became standard references, including works on Magnentius, Postumus's bronze coinage, and "Monnaie et donativa au Bas-Empire". His comprehensive three-volume work on imperial coin busts represents the summation of his expertise in analyzing both the artistic and historical dimensions of Roman coinage.