The Persian Boy is a 1972 historical novel written by Mary Renault and narrated by Bagoas, a young Persian from an aristocratic family who is captured by his father's enemies, castrated, and sold as a slave to king Darius III, who makes him his favourite. Eventually he becomes the lover and most faithful servant of Alexander the Great, who overthrew Darius and captured the Persian Empire. Bagoas' narration provides both a Persian view of the conquest and an intimate look at the personality of the conqueror. In Renault's view, Alexander's love for Bagoas influenced his desire to unite the Greek and Persian peoples. Renault also posits the notion that Alexander's relentless drive to conquer the world stemmed in part from his troubled relationship with his domineering mother, and his desire to "escape" from her influence by leading his army ever eastward.

Eileen Mary Challans, known by her pen name Mary Renault, was a British writer best known for her historical novels set in ancient Greece.