Constantine Phaulkon (Greek: Κωνσταντῖνος Γεράκης, Konstantinos Gerakis; γεράκι is the Greek word for "falcon"; 1647 – 5 June 1688, also known as Costantin Gerachi, Constantino Falcão in Portuguese and simply as Monsieur Constance in French) was a Greek adventurer who became the prime counsellor to King Narai of Ayutthaya and assumed the Thai noble title Chao Phraya Wichayen (เจ้าพระยาวิชาเยนทร์).