The paradynasteuōn was a term used, especially in the Byzantine Empire

Byzantine Empire

The Byzantine Empire was the Eastern Roman Empire during the periods of Late Antiquity and the Middle Ages, centred on the capital of Constantinople. Known simply as the Roman Empire or Romania to its inhabitants and neighbours, the Empire was the direct continuation of the Ancient Roman State...

, to designate a ruler's favorite, often raised to the position of chief minister. Probably deriving from Thucydides

Thucydides

Thucydides was a Greek historian and author from Alimos. His History of the Peloponnesian War recounts the 5th century BC war between Sparta and Athens to the year 411 BC...

, it was used in the later

Late Antiquity

Late Antiquity is a periodization used by historians to describe the time of transition from Classical Antiquity to the Middle Ages, in both mainland Europe and the Mediterranean world. Precise boundaries for the period are a matter of debate, but noted historian of the period Peter Brown proposed...

 Roman Empire

Roman Empire

The Roman Empire was the post-Republican period of the ancient Roman civilization, characterised by an autocratic form of government and large territorial holdings in Europe and around the Mediterranean....

 for people with great authority. It was not an official title or position, but the term was extensively used by chroniclers such as Theophanes the Confessor

Theophanes the Confessor

Saint Theophanes Confessor was a member of the Byzantine aristocracy, who became a monk and chronicler. He is venerated on March 12 in the Roman Catholic and the Eastern Orthodox Church .-Biography:Theophanes was born in Constantinople of wealthy and noble iconodule parents: Isaac,...

 or Theophanes Continuatus

Theophanes Continuatus

Theophanes Continuatus or Scriptores post Theophanem is the Latin name commonly applied to a collection of historical writings preserved in the 11th-century Vat. gr. 167 manuscript. Its name derives from its role as the continuation, covering the years 813–961, of the chronicle of Theophanes the...

 to designate an emperor's closest aide and chief minister. It gained greater currency during the Komnenian period and continued to be used by historians of the Palaiologan period, although the more technical term of mesazōn

Mesazon

The mesazōn 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 Emperor.- History and functions :...

("mediator"), which eventually came to correspond to an actual office, had largely replaced it.