The () was a high dignitary and official during the last centuries of the Byzantine Empire, who acted as the chief minister and principal aide of the Byzantine emperor. History and functions The term's origins lie in the 10th century, when senior ministers were sometimes referred to as the (), i.e. 'mediators' between the emperor and his subjects (cf. ). The title first became official in the mid-11th century, when it was conferred to Constantine Leichoudes, the future Ecumenical Patriarch of Constantinople. In the Komnenian period, it was awarded to senior government officials who functioned as de facto prime ministers, such as the and the , but had not yet acquired a permanent and specific function, nor the power that would characterize it in later years. Rather, it was a title bestowed on the principal imperial secretary of the moment, who acted precisely as an "intermediary" between the emperor and other officials. This reflected the shift of the Byzantine government under the Komnenoi from the old Roman-style bureaucracy to a more restricted, aristocratic ruling class, where government was exercised within the imperial household, as in feudal Western Europe. The office of became formally institutionalized in the Empire of Nicaea, where the holder of the (as the function had become known), served as the Empire's chief minister, coordinating the other ministers. As the emperor and historian John VI Kantakouzenos () records, the was "needed by the emperor day and night". This arrangement was inherited by the restored Palaiologan-era Empire and continued in use until the Fall of Constantinople in May 1453. The office was also used in the same function in the Byzantine courts of Epirus, Morea, and Trebizond. In the latter case, it acquired the epithet ('great'). List of Constantine Leichoudes, until 1050. Theodore Styppeiotes, under Emperor Manuel I Komnenos (). John Kamateros, under Emperor Manuel I Komnenos. Michael Hagiotheodorites, under Emperor Manuel I Komnenos. Theodore Maurozomes, under Emperor Manuel I Komnenos. Demetrios Komnenos Tornikes, under Emperor John III Vatatzes (). Theodore Mouzalon, until 1294. Nikephoros Choumnos, 1294–1305, under Emperor Andronikos II Palaiologos (). Theodore Metochites, 1305–1328, under Emperor Andronikos II Palaiologos. Alexios Apokaukos, 1328–1345, under Emperors Andronikos III Palaiologos () and John V Palaiologos (r. 1341–1391). Demetrios Kydones, 1347–1354, under Emperor John VI Kantakouzenos (); 1369–1383 under Emperor John V Palaiologos; 1391–1396 under Emperor Manuel II Palaiologos (). Demetrios Palaiologos Goudeles, from the late reign of John V Palaiologos