Sergius of Reshaina (died 536) was an Syriac physician and priest during the 6th century. He is best known for translating medical works from Greek to Syriac, which were eventually translated to Arabic. Reshaina, where he lived, is located about midway between the then intellectual centres of Edessa and Nisibis, in Northern Mesapotamia.
The great ninth century translator Hunain ibn Ishaq gives the names of twenty six medical texts by Galen which Sergius translated into Syriac; these were the first significant translations of medical works from Greek into a Semitic language, and presumably were the textbooks Sergius himself had used when he studied at Alexandria. Hunain is not always complimentary about Sergius's translations; though some he thinks are better, as Sergius became more experienced. Sergius also translated various other works, including the Categories of Aristotle, Porphyry's Introduction to the Categories and theological works by Pseudo-Dionysius the Areopagite. He also composed two works of his own, On the Influence of the Moon, and The Movement on the Sun, probably drawing heavily on Greek sources.
Although Sergius kept in close contact with the mostly Nestorian scholars nearby, he was himself in fact a Monophysite Christian priest. In 535 he was sent to Rome by Ephrem, Orthodox Patriarch of Antioch, and escorted Pope Agapetus I to Constantinople. There he died, the following year.