Koy Thuon was a Cambodian politician, intellectual and a member of the Central Committee of the Khmer Rouge. A former high school teacher, he had joined the revolutionary movement in the 1960s and had risen to become Finance Minister of Democratic Kampuchea and leader of the Northern Zone before being arrested along with all his colleagues and associates in 1977, sent to the infamous S-21 concentration camp. He was replaced by Ta Pok as the leader of the Northern Zone and executed the same year he was arrested.