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. Works (Lat. De Actionibus et Affectibus Spiritus Animalis, ejusque Nutritione). This is a psychological and physiological work in two books, in which all his reasoning seems to be founded upon the principles laid down by Aristotle, Galen, and others, with relation to the same subject. The style of this tract is by no means impure, and has a great mixture of the old Attic in it, which is very rarely to be met with in the later Greek writers. A tolerably full abstract of it is given by Barchusen. It was first published in a Latin translation by Giulio Alessandrini in 1547. The first edition of the original was published in 1557, edited, without notes or preface, by Jac. Goupyl. A second Greek edition appeared in 1774, under the care of J. F. Fischer. Ideler has also inserted it in the first volume of his Physici et Medici Graeci Minores (1841); and the first part of J. S. Bernardi Reliquiae Medico-Criticae (1795) contains some Greek Scholia on the work. (Lat. De Methodo Medendi). Six books which have hitherto appeared complete only in a Latin translation, though Dietz had, before his death, collected materials for a Greek edition of this and his other works. In these books, says Friend, though he chiefly follows Galen, and very often Aëtius Amidenus and