The megas logothetes was an official who served as effective foreign minister of the Byzantine Empire, in the period from c. 1250 to c. 1350, after which it continued as an honorific dignity. The office evolved from the Komnenian-era logothetes ton sekreton, and was established during the Empire of Nicaea. Its holders were frequently distinguished scholars, who played a prominent role in the civil and military affairs of their time; three of its holders also served in tandem as the head of the civil administration and effective prime minister of the Empire. The title was also used in the Empire of Trebizond. After the fall of Constantinople, it was adopted in the Danubian Principalities as an honorific title for laymen in the Ecumenical Patriarchate of Constantinople.

Logothete was an administrative title originating in the eastern Roman Empire. In the middle and late Byzantine Empire, it rose to become a senior administrative title, equivalent to a minister or secretary of state. The title spread to other states influenced by Byzantine culture, such as Bulgaria, Sicily, Serbia, and the Danubian Principalities.