Demetrios Kydones

Demetrios Kydones, latinized as Demetrius Cydones or Demetrius Cydonius (Greek: Δημήτριος Κυδώνης; 1324, Thessalonica – 1398, Crete), was a Byzantine Catholic theologian, translator, author and statesman. He 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.

As Imperial Premier, Kydones' West-Politik effort during his second and third stints was to bring about a reconciliation of the Eastern Orthodox and Catholic Churches, in order to cement a military alliance against the ever-encroaching Islamic conquests, a program that culminated in John V Palaiologos' reconciliation with Catholicism.

His younger brother and somewhat-collaborator in his efforts was the noted anti-Palamite theologian Prochoros Kydones.