Who is Head Black Eunuch from Persian Letters. Translated with an Introd. and Notes, by C. J. Betts and what is their importance?

The Head Black Eunuch is in charge of Usbek's seraglio while he is away on his trip to Europe. Kidnapped from Africa at the age of fifteen, he was castrated and put to work in a seraglio that housed more than twenty women. Although the Head Black Eunuch believes he knows how to properly control the women in Usbek's seraglio, he isn;t allowed to because of his master's kind heart.