John VI Kantakouzenos
Demetrios Kydones, Latinized as Demetrius Cydones or Demetrius Cydonius (; 1324, Thessalonica – 1398, Crete), was a Byzantine theologian, translator, writer and influential statesman, who served an unprecedented three terms as "Mesazon" (Imperial Prime Minister or Chancellor) of the Byzantine Empire under three successive emperors: John VI Kantakouzenos, John V Palaiologos and Manuel II Palaiologos.