Eunuchs have been an indispensable part in Near and Middle Eastern societies. As close and trustful envoys of their patrons in authoritative and public positions, eunuchs are already known in Mesopotamia, Persia, Byzantium as well as in China and in classical antiquity. Castration, even if it was well known for some therapeutic purpose, was in Muslim societies highly problematic but it seems that male slaves were not castrated on Muslim territory but in specific centres on the border with non-Muslim territories. The occupation of eunuchs since they were already castrated was, at least in the Abbasid period in which we observe an increasing visibility of eunuchs in the public space, an accepted practice at the imperial court of the caliph and in elite society. In contrast to ordinary slaves eunuchs have been exceptional and often powerful trustees of their patrons who at the same time have been completely dependent on their patrons and deserved and kept their positions only due to the deep trust of their patron.