Marcellus Empiricus, also known as Marcellus Burdigalensis (“Marcellus of Bordeaux”), was a Latin medical writer from Gaul at the turn of the 4th and 5th centuries. His only extant work is the De medicamentis, a compendium of pharmacological preparations drawing on the work of multiple medical and scientific writers as well as on folk remedies and magic. It is a significant if quirky text in the history of European medical writing, an infrequent subject of monographs, but regularly mined as a source for magic charms, Celtic herbology and lore, and the linguistic study of Gaulish and Vulgar Latin.[1] Bonus auctor est (“he’s a good authority”) was the judgment of J.J. Scaliger,[2] while the science historian George Sarton called the De medicamentis an “extraordinary mixture of traditional knowledge, popular (Celtic) medicine, and rank superstition.”[3] Marcellus is usually identified with the magister officiorum of that name who held office during the reign of Theodosius I.