thumb|300px|Gold [[aureus with the legend ""]]
Sponsianus, also known in English as Sponsian, may have been a Roman usurper during the third century. His existence is implied by a series of coins bearing his name, ostensibly part of a hoard excavated in the eighteenth century.
No corresponding figure named Sponsianus is mentioned in any ancient sources, and the coins are widely believed to be the work of modern forgers. However, a study of wear marks on the coins published in November 2022 concluded that the coins were authentic, supporting Sponsian's existence as a historical figure. The study's methodology and conclusions have been criticized by a number of scholars.
Scholars who accept the historicity of Sponsianus date his activity to the Crisis of the Third Century, often locating him in the particularly unstable province of Dacia. More precise dating is a matter of controversy: some scholars have conjectured that he may have proclaimed himself emperor in the 260s, after Dacia was cut off from the rest of the Empire, or in the early 270s after it was formally abandoned by Aurelian. Others contend he may have been active earlier, during the reign of Philip the Arab or his son, Philip II.
Discussion
Physical description and provenance
The sole evidence for the existence of Sponsianus is his name on a few double-aurei reportedly uncovered in a coin-hoard in Transylvania in 1713, and subsequently dispersed among several collections. One was kept in the Hunterian Museum at Glasgow University, alongside three coins depicting other figures also claimed to have been from the hoard. Another entered the bequest of Baron Samuel von Brukenthal, a Habsburg governor of Transylvania.
Traditional numismatic analysis
The traditional consensus among numismatists has been to regard the coins as modern forgeries. As early as 1828, Eckhel noted the strangeness of the coins and concluded against the historicity of Sponsianus. In 1868, the French numismatist Henri Cohen dismissed them as "very poor quality modern forgeries," and 1923 analysis, concluding that the coins were modern forgeries, is considered definitive by many numismatists. Other scholars concur with the RIC, and classify the coins as third-century imitations of Roman coinage, while still others contend that the coins can be ascribed to a historical usurper Sponsianus. In general, ancient historians have been more willing to accept the historicity of Sponsianus and the authenticity of the coins. The study attracted significant scholarly and media attention, and led the Brukenthal Museum in Sibiu to reclassify another coin bearing Sponsianus' image as genuine. Richard Abdy,<!--Q42559466--> the curator of the collection of Roman coins at the British Museum, condemned the study, stating "they've gone full fantasy." In the Journal Antigone, Alfred Deahl argued that the coins are forgeries, drawing attention to the unusual features of the coins as well as the oddness of the other coins purportedly found in the same hoard.