Eunuchs (in Greek οἱ εὐνοῦχοι) were an extremely important and numerous category of courtiers of the Byzantine Emperor. Their main purpose was to serve the emperor and empress in the chambers of the Great Palace; only they could be fully trusted by the emperor. Because of their unfettered access to the emperor's person, the eunuchs, who had their own court hierarchy, controlled the administration of the state for most of Byzantine history.
Eunuchs were highly privileged in Byzantine society. Although they could not occupy the imperial throne and their legal rights were limited in some respects, eunuchs otherwise had very attractive prospects. Although the main source of eunuchs in Byzantium was slaves from neighboring countries, it was not uncommon for the younger sons of noble families to be castrated. For example, two of the sons of Emperor Romanos I Lekapenos were castrated — Theophylact, who later became Patriarch, and Basil, the de facto ruler of the empire in 945-985. In general, eunuchs had the opportunity to excel in any professional field. Beginning in the 6th century, eunuchs held high positions at the head of the Byzantine army and navy, although they rarely achieved success in this field.
Eunuchs were much rarer in the lower ranks of society.