The megas logothetēs (Greek: μέγας λογοθέτης) or Grand Logothete, was an official supervising all the sekreta (or the fiscal departments) of the Byzantine Empire.
History and functions 
The post was first established by Emperor Alexios I Komnenos (r. 1081–1118) as the logothetēs tōn sekretōn (Greek: λογοθέτης τῶν σεκρέτων), in an attempt to improve the coordination of the various departments (sekreta). The fiscal departments in particular were further grouped under two other officials: the two principal treasury departments, the genikon and eidikon, were put under the megas logariastēs ("grand accountant") of the sekreta (Greek: μέγας λογαριαστής τῶν σεκρέτων), while another megas logariastēs (Greek: μέγας λογαριαστής τῶν εὐαγῶν σεκρέτων) oversaw the "pious bureaux" (Greek: εὐαγή σεκρέτα, euagē sekreta), i.e. imperial estates and religious foundations. By the mid-12th century, the logothetēs tōn sekretōn had become the megas logothetēs, an office which survived until the Fall of Constantinople in May 1453.
Today, the leading offikion among the archons of the Ecumenical Patriarchate of Constantinople still bears the title of "Grand Logothete".
Further reading