A diplomatic agent is a person who is appointed by a government to represent it in foreign countries. An ENVOY (5 letters) is a diplomatic agent who is sent on a special mission, usually to negotiate a treaty or other agreement. An EMISSARY (8 letters) is a diplomatic agent who is sent to represent a government in a foreign country. A plenipotentiary (15 letters) is a diplomatic agent who is given full authority to represent a government in negotiations with foreign governments.