Bagoas and Wikipedia
Bagoas (or Βαγώας, Greek transcription of Old Persian Bagoi; died 336 BC) was a eunuch who became the confidential minister of Artaxerxes III. He threw in his lot with the Rhodian condottiere Mentor, and with his help succeeded in subjecting Egypt again to the Persian empire (probably 342 BC). Mentor became general of the maritime provinces, suppressed the rebels, and sent Greek mercenaries to the king, while Bagoas administered the upper satrapies and gained such power that he was the real master of the kingdom (Diod. xvi. 50; cf. Didymus, Comm. in Demosth. Phil. vi. 5).
He became very wealthy by confiscating the sacred writings of the Egyptian temples and giving them back to the priests for large bribes (Diod. XVI. 51). When the high priest of Jerusalem murdered his brother Johannes in the temple, Bagoas (who had supported Johannes) put a new tax on the Jews and entered the temple, saying that he was purer than the murderer who performed the priestly office (Joseph. Ant. xi. 7.1).
In 338 BC Bagoas killed the king and all his sons but the youngest, Arses, whom he raised to the throne; two years later he murdered Arses and made Darius III king. When Darius attempted to become independent of the powerful vizier, Bagoas tried to poison him too; but Darius was warned and forced him to drink the poison himself (Diod. xvii. 5; Johann. Antioch, p. 38, 39 ed. Müller; Arrian ii. 14. 5; Curt. vi. 4. 10).
A later story, that Bagoas was an Egyptian and killed Artaxerxes III because he had killed the sacred Apis (Aelian, Var. Hist. vi. 8), is without historical basis.
Bagoas' house in Susa, with rich treasures, was presented by Alexander to Parmenion (Plut. Alex. 39); his gardens in Babylon, with the best species of palms, are mentioned by Theophrastus (Hist. Plant, ii. 6; Plin. Nat. Hist. xiii. 41).
Plutarch reports an angry letter from Alexander to Darius, naming Bagoas as one of the persons that organized the murder of his father, Philip II.