Joannes Actuarius
Johannes Zacharias Actuarius (; – c. 1328), son of Zacharias (), was a Byzantine physician in Constantinople. He is given the title of "Actuarius", a dignity frequently conferred at that court upon physicians. Biography. Very little is known of the events of Actuarius' life, and his dates are debated, as some reckon him to have lived in the eleventh century, and others place him as recently as the beginning of the fourteenth. He probably lived towards the end of the thirteenth century, as one of his works is dedicated to his tutor, Joseph Racendytes, who lived in the reign of Andronikos  II Palaiologos (1282–1328). One of his school-fellows is supposed to have been Apocauchus, whom he describes (though without naming him) as going upon an embassy to the north. Actuarius wrote several books on medicinal subjects, particularly, an extensive treatise about the urines and uroscopy. Around 1299, he considered moving to Thessaloniki, but decided to stay in Constantinople; later, he was appointed chief physician to the Emperor. Some of Actuarius' works were translated into Latin, and published in the 16th century.